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• Published: 22 June 2021

The widespread and unjust drinking water and clean water crisis in the United States

• J. Tom Mueller   ORCID: orcid.org/0000-0001-6223-4505 1 &
• Stephen Gasteyer 2  

Nature Communications volume  12 , Article number:  3544 ( 2021 ) Cite this article

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An Addendum to this article was published on 13 June 2023

An Author Correction to this article was published on 13 June 2023

Many households in the United States face issues of incomplete plumbing and poor water quality. Prior scholarship on this issue has focused on one dimension of water hardship at a time, leaving the full picture incomplete. Here we begin to complete this picture by documenting incomplete plumbing and poor drinking water quality for the entire United States, as well as poor wastewater quality for the 39 states and territories where data is reliable. In doing so, we find evidence of a regionally-clustered, socially unequal household water crisis. Using data from the American Community Survey and the Environmental Protection Agency, we show there are 489,836 households lacking complete plumbing, 1,165 community water systems in Safe Drinking Water Act Serious Violation, and 9,457 Clean Water Act permittees in Significant Noncompliance. Further, elevated levels of water hardship are associated with rurality, poverty, indigeneity, education, and age—representing a nationwide environmental injustice.

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Introduction

Both in and out of the country, most presume that residents of the United States live with close to universal access to potable water and sanitation. The United Nations Sustainable Development Goals Tracker, which tracks progress toward meeting Sustainable Development Goal Number 6—calling for universal access to potable water and sanitation for all by 2030—estimates that 99.2% of the US population has continuous access to potable water and 88.9% has access to sanitation 1 . By percentages and the lived experience of most Americans, this appears accurate. The American Community Survey shows that from 2014 to 2018 only an estimated 0.41% of occupied US households lacked access to complete plumbing—meaning access to hot and cold water, a sink with a faucet, and a bath or shower. Although this relative percentage may be low, this 0.41% corresponds to 489,836 households spread unevenly across the country, making the absolute number quite troubling. These numbers become even more dramatic when we broaden our scope to poor household water quality, where the estimates we provide in this paper show the issue affects a far greater share of the population (Table  1 ).

This study builds on a growing body of evidence showing access to plumbing, water quality, and basic sanitation are lacking for a disturbingly large number of US residents by providing a definitive picture of the ongoing household water crisis in the United States. Water and sanitation issues have been a growing concern in the United States, particularly among policy organizations, for the past 20 years 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 . For example, the now-dated Still Living without the Basics report used Census data from 2000 to show that more than 670,000 households (0.64% of households and 1.7 million people) lacked access to complete plumbing facilities 7 . Further, the Water Infrastructure Network published a report in 2004 citing a gap of $23 billion between available funding and needed water and sanitation infrastructure investments 6 . In line with this, the American Society of Civil Engineers has repeatedly given the United States a “D” grade for water infrastructure, and “D-” for wastewater infrastructure in their annual “Infrastructure Report Card” 11 . Although water hardship in the United States has experienced some academic attention, much of the work has become dated and has generally focused on a single dimension of the issue at a time—for example, recent scholarship has focused on exclusively incomplete plumbing 3 , 4 , 9 , water quality 5 , 10 , or on only urban parts of the country 2 . This has left our understanding of the scope of the issue incomplete. In this paper, we estimate and map the full scope of water hardship for the dimensions of incomplete plumbing and poor drinking water quality across the entire United States, while also estimating and mapping the scope of poor wastewater quality for the 39 states where EPA data is reliable, in order to complete this picture.

Prior work from academics and policy groups on dimensions of water hardship has found water access issues pattern along common social inequalities in the United States. The Natural Resources Defense Council released a report demonstrating the disproportionate impact on people of color posed by Safe Drinking Water and Clean Water Act regulatory burdens 12 , which built on similar peer reviewed findings 13 , 14 . Furthermore, both policy papers and peer reviewed studies have analyzed Census data to estimate the population lacking access to complete plumbing facilities and clean water 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 12 . The studies suggest low-income and non-White people—particularly indigenous populations who continue to face injustices related to legacies of settler colonialism 15 —are significantly more likely to have incomplete plumbing and unclean water 3 , 12 . Further, it appears incomplete plumbing may be a disproportionately rural issue, while poor water quality may be a disproportionately urban issue 5 , 9 . Direct comparisons, as we perform here, are needed to fully establish the variability of this inequality between dimensions of water hardship.

The prior scholarship on the inequitable distribution of plumbing and pollution speaks to the well-documented environmental injustices found throughout the United States. Environmental injustice, meaning the absence of “fair treatment and meaningful involvement of all people regardless of race, color, national origin, or income with respect to the development, implementation, and enforcement of environmental laws, regulations, and policies” (p. 558) 16 , has been documented in the United States along the social dimensions of income 17 , 18 , poverty 19 , race and ethnicity 20 , 21 , age 22 , education 22 , 23 , and rurality 22 , 24 , 25 . Based on the evidence of prior work on water hardship, it is clear household water access represents an ongoing environmental injustice in the United States 5 . However, the specific dimensions of this injustice, and how they vary between type of water hardship remain largely unknown. To address this gap, we estimate models of water injustice for the previously identified social dimensions at the county level for elevated levels of both incomplete plumbing and poor water quality.

Level of water hardship in the United States

Based upon the most recent available data reported by both the United States Census Bureau via the American Community Survey and the Environmental Protection Agency via Enforcement and Compliance History Online, we find that incomplete plumbing and poor water quality affects millions of Americans as of 2014–2018 and August 2020, respectively (Table  1 ) 26 , 27 . A total of 0.41% of households, or 489,836 households, lacked complete plumbing from 2014–2018 in the United States. Further, 509 counties, representing over 13 million Americans, have an elevated level of the issue where >1% of household do not have complete indoor plumbing (Table  2 ). Thus, even if individuals are not experiencing the issue themselves, they may live in a community where incomplete plumbing is a serious issue.

The portion of the population affected by poor water quality is much greater than that of incomplete plumbing. Poor water quality in our analysis is indicated in two ways, (1) Safe Drinking Water Act Serious Violators and (2) Clean Water Act Significant Noncompliance. For the first, community water systems are regulated under the Safe Drinking Water Act and are scored based on their violation and compliance history, those community water systems that are the most problematic are recorded as Serious Violators by the Environmental Protection Agency 27 . Second, any facility that discharges directly into waters in the United States is issued a Clean Water Act permit. Those which “hold a more severe level of environmental threat” are ruled as being in Significant Noncompliance 27 . Importantly, although data on Safe Drinking Water Act Serious Violators is available nationwide, the Clean Water Act data reported by the EPA is known to be inaccurate for 13 states. Thus, although we can draw national conclusions for incomplete plumbing and Safe Drinking Water Act violations, our understanding of Clean Water Act violations is limited to the 39 states and territories for which data are available and reliable.

Using these two measures of poor water quality, we find 2.44% of community water systems, a total of 1165, were Safe Drinking Water Act Serious Violators and 3.37% of Clean Water Act permittees in the 39 states and territories with accurate data (see Methods for more details), a total of 9457, were in Significant Noncompliance as of 18 August 2020. At the county level, this corresponds to an average of 2.86% of county community water systems being listed as Safe Drinking Water Act Significant Violators and an average of 6.23% of county Clean Water Act permittees being listed as Significant Noncompliers. Due to limitations in the data, we are unable to determine exactly how many individuals are linked to each problematic community water system or Clean Water Act permittee, however, we do find that over 81 million Americans live in counties where >1% of community water systems are listed as Significant Violators, and more than 153 million Americans in the 39 reliable states and territories live in counties where greater than one percent of Clean Water Act permittees are Significant Noncompliers. Thus, although the number of individuals impacted by these issues is certainly far smaller than these totals, a vast number of Americans live in communities where issues of water quality are elevated.

Due to our conservative approach of removing all states with Clean Water Act data issues, we test the sensitivity of our estimates by also calculating supplemental estimates of Clean Water Act Significant Noncompliance under two counterfactual scenarios. In the first, we include the data as-is from the EPA for all counties in the 50 states, DC, and Puerto Rico, and in the second, we duplicate the counties in the top and bottom 20% of Significant Noncompliance in states without data issues—with the rationale being that the 945 counties removed due to poor data represented roughly 40% of the total counties remaining when problems states were removed. Thus, this attempts to simulate total counts if those removed were balanced between very high and very low levels of noncompliance. Results using all EPA data increase national estimates of Significant Noncompliance (Tables 3 and 4 ), with the total percent of permittees in this status jumping from 3.37% to 6.01%. While the duplication test does raise our estimates, it is not nearly as dramatic, with the percent of permittees in Significant Noncompliance only rising to 3.87%. These results make sense given that the most common reason for data issues was an overreporting of noncompliance within states.

When looking at the issue spatially, we can see that while water hardship affects all parts of the country to some degree, the issues are clustered in space (Figs.  1 – 3 ). Importantly, the clustering varies between each water issue. Incomplete plumbing is clustered in the Four Corners, Alaska, Puerto Rico, the borderlands of Texas, and parts of Appalachia (Fig.  1 ); Safe Drinking Water Act Serious Violators are clustered in Appalachia, New Mexico, Alaska, Puerto Rico, and the Northern Intermountain West (Fig.  2 ); and Clean Water Act Significant Noncompliance clearly follows state boundaries—likely speaking to variable monitoring by state. Although spatial representation is limited by the absence of 13 states with inaccurate EPA data, we can still see that Clean Water Act Significant Noncompliance is clustered in the Intermountain West, the Upper Midwest, Appalachia, and the lower Mississippi (Fig. 3 ). These regional clusters persist when we include the problem states, which is visible in the map included in the Supplemental Information (Supplementary Figure 1 ).

Households are determined to have incomplete plumbing if they do not have access to hot and cold water, a sink with a faucet, a bath or shower, and—up until 2016—a flush toilet.

Safe Drinking Water Act Serious Violators are those community water systems regarded by the Environmental Protection Agency as the most problematic due to violation and compliance history.

All facilities that discharge directly into water of the United States are issued a Clean Water Act permit, those who represent a more severe level of environmental threat due to violations and noncompliance are considered in Significant Noncompliance.

Water injustice modeling

Although we can easily see clustering by space in Figs.  1 through 3 , the maps do not tell us whether or not incomplete plumbing and poor water quality are also clustered by social dimensions, which would represent an environmental injustice. To assess this social clustering, we estimate linear probability models of elevated levels of incomplete plumbing and poor water quality with the previously identified environmental justice dimensions of age, income, poverty, race, ethnicity, education, and rurality as our independent variables. We include these independent variables due to their prevalence within prior work on environmental injustice in both rural and urban areas 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 . Further, although there is not a one-to-one overlap, these variables conceptually map onto the dimensions of the Center for Disease Control Social Vulnerability Index: Socioeconomic Status (i.e. income, poverty, education), Household Composition & Disability (i.e. age), Minority Status & Language (i.e. race and ethnicity), and Housing & Transportation (i.e. rurality) 28 .

For each outcome, we first estimate purely descriptive models with only one dimension of injustice included at a time, and then estimate a full model with all dimensions included. The outcomes are dichotomous measures of whether or not a county had >1% of households with incomplete plumbing, >1% of community water systems listed as Serious Violators, or >1% of Clean Water Act permittees in Significant Noncompliance. All descriptive statistics for the dichotomous outcomes are presented in Table 2 . Descriptive statistics for the continuous independent variables are presented in Supplementary Information (Supplementary Table  1 ). Here we present the outcomes of the purely descriptive models visually in Fig.  4 and discuss the full models in the narrative. Full regression results, including exact 95% confidence intervals and p -values, for all models are available in Supplementary Information (Supplementary Tables  2 , 3 and 4 ).

Different colors for plotted coefficients represent separate blocks of variables. Models are linear probability models with state fixed effects and cluster-robust standard errors at the state level. All tests two-tailed. Dots indicate point estimates and lines represent 95% confidence intervals. Models predicted elevated levels of each dimension of water hardship. For incomplete plumbing this is indicated by >1% of households in a county having incomplete plumbing ( N  = 3219). For Safe Drinking Water Act (SDWA) Serious Violation this is indicated by >1% of active community water systems being considered Serious Violators ( N  = 3143). For Clean Water Act (CWA) Significant Non-Compliance this is indicated by >1% of Clean Water Act permittees being considered in Significant Non-Compliance ( N  = 2261). Full model results, confidence intervals, and exact p -values available in SI.

We find elevated levels of incomplete plumbing at the county level were significantly ( p  < 0.05) associated with older populations, lower income, higher poverty, greater portions of indigenous people (American Indian, Alaska Natives, Native Hawaiian, and Other Pacific Islanders), lower levels of education, and more rural counties (Fig.  4 ). A great deal of these associations persisted in a full model with all dimensions of injustice (Supplementary Table  2 ). The only differences between the full model and the series of purely descriptive models were that income, percent with at least a bachelor’s degree, and non-metropolitan metropolitan adjacency were no longer significantly associated with elevated levels of incomplete plumbing. This indicates that the inequalities in plumbing access along the dimensions of age, poverty, indigeneity, low education, and extreme rurality persist at the county level, even when accounting for the other dimensions of environmental injustice.

The models for elevated levels of Safe Drinking Water Act Serious Violators indicated less social inequality than the models for incomplete plumbing. The purely descriptive models found elevated levels of Serious Violators were associated with higher income, higher poverty, and metropolitan counties (Fig.  4 ). The full model had minor variation, with median household income no longer being significant in the model (Supplementary Table  3 ). Thus, the full model shows that the association between elevated levels of Serious Violators and higher poverty and metropolitan status persists even when considering other social dimensions.

We see the fewest indicators of water injustice for elevated levels of Clean Water Act Significant Noncompliance—which only include counties within the 39 states and territories with accurate data. In the purely descriptive models, we find older populations, more Latino/a counties, less educated counties, and remote rural counties were significant less likely to have elevated levels of noncompliance (Fig. 4 ). In the full model, the association for education is no longer significant but age, Latino/a, and rurality remain (Supplementary Table 4 ). Similar to our national estimates, we also conducted model sensitivity tests using the same scenarios described above. As shown in Fig. 5 , neither scenario substantively changes our conclusions, with the only changes in significance being for percent Latino/a and percent without a high school diploma—both of which were only marginally significant in our primary models ( p  > 0.01).

Descriptive regression model results. Different colors for plotted coefficients represent separate blocks of variables. Models are linear probability models with state fixed effects and Huber/White/Sandwich cluster-robust standard errors at the state level. All tests are two-tailed. Dots indicate point estimates and lines represent 95% confidence intervals. Models predicted whether or not there were greater than 1% of Clean Water Act permittees being considered in Significant Noncompliance in the county. First model excludes counties in states with CWA data issues ( N  = 2261), second model includes all counties reported by the EPA ( N  = 3206), third model duplicates counties in the top and bottom 10% of CWA Significant Noncompliance within states without data issues ( N  = 3151). Full model results, confidence intervals, and exact p values available in SI.

Our findings demonstrate that the problem of water hardship in the United States is hidden, but not rare. Indeed, millions live in counties where more than 1 out of 100 occupied households lack complete plumbing. Millions more live in places with chronic Safe Drinking Water Act violations and Clean Water Act noncompliance. We present this paper to help sound the alarm of this significant household water crisis in the United States. Although the relative share of Americans experiencing this problem is low, the absolute number of people dealing with incomplete plumbing—a total of 489,836 households—and poor water quality—1165 community water systems nationwide and 9457 Clean Water Act permittees in the 39 accurate states and territories—remains quite high. Further, given the water infrastructure of the United States, consistently deemed as poor by experts 6 , 11 , if action is not taken the situation may only get worse.

These findings are even more concerning when considering that water hardship is spread unevenly across both space and society, reflecting the spatial patterning of social inequality due to settler colonialism, racism, and economic inequality in the United States. Figures  1 , 2 , and 3 document the clear regional clustering of these issues and our models of environmental injustice demonstrate the social inequalities found for this form of hardship. Particularly in the case of incomplete plumbing, we find significant environmental injustice at the county level along the social dimensions of age, income, poverty, indigeneity, education, and rurality. These associations certainly stem from multiple causal pathways—for example associations with indigeneity likely stem from legacies of injustice as well as ongoing policies placing limitations on land use and infrastructure development on American Indian reservations 15 . Remedying these injustices will require careful attention to the root causes of the problem. It is important to note that the signs of injustice for poor water quality were less clear than for incomplete plumbing, with far fewer significant associations. Further, the minimal support for injustice in the case of Clean Water Act Significant Noncompliance was evident in all three specifications of counties in our sensitivity tests. Suggesting that the removal of the states with data issues did little to impact coefficient estimates. These differences between dimensions of water hardship highlight the nuance between each of these specific forms of water hardship, and suggest a one-size-fits-all approach to remedying this crisis is unlikely to be effective. This need for place-based policy is made stark when we view the obvious state level differences in Clean Water Act Significant Noncompliance in Fig. 3 . A clear direction for future work is to investigate the cause of these notable state-level differences.

The household water access and quality crisis we have identified here is solvable. Policy is needed to specifically address these issues and bring this problem into the spotlight. However, as indicated by the persistently high levels of Safe Drinking Water Act Serious Violation and Clean Water Act Significant Noncompliance, any policy put in place must be enforceable and strong. As it currently stands, counties with elevated levels of incomplete plumbing and poor water quality in America—which are variously likely to be more indigenous, less educated, older, and poorer—are continuing to slip through the cracks.

Data sources

Data for this analysis were extracted from the American Community Survey (ACS) 5-year estimates for 2014–2018 via Integrated Public Use Microdata Series – National Historic Geographic information System (IPUMS-NHGIS) 26 , and from the Environmental Protection Agency’s (EPA) Enforcement and Compliance History Online (ECHO) Exporter 27 . Data were extracted at the county level for all 50 states, Washington DC, and Puerto Rico–the two non-state entities with available data. The ACS is an ongoing survey of the United States which documents a wide variety of social statistics ranging from simple population counts to housing characteristics. Due to the staggered sampling structure of the ACS, it takes 5 years for every county to be sampled. Because of this, researchers must use 5-year intervals to ensure complete data coverage. The data from these 5 years are projected into estimates for all counties in the United States for the 5-year period in question. As of this study, 2014–2018 was the most recently available data.

ECHO collates data from EPA-regulated facilities across the United States of America to report compliance, violation, and penalty information for all facilities for the most recent 5-year interval. ECHO data is updated weekly and the data for this paper was extracted on 18 August 2020. This means that the data in our analysis represents the status of each community water system or Clean Water Act permittee, as reported by the EPA, as of 18 August 2020. Only those community water systems or Clean Water Act permittees listed as Active by ECHO were included in this analysis. As ECHO data is at the level of the water system, permittee, or utility, we aggregated data up to the county level.

Safe Drinking Water Act data was geolocated using QGIS 3.10 based upon latitude and longitude. This was done because other geographic identifiers for the Safe Drinking Water Act data were often missing. In line with prior work 4 , 5 , 7 , 8 , and in order to facilitate a cleaner dataset, we only focus on those water systems labeled community water systems for our analysis. Community water systems were geolocated based upon the county in which their latitude and longitude were located, if a community water system had latitude and longitude over water, a nearest neighbor join was used. In total, 1334 out of 49,479 community water systems were dropped because of there being no reported latitude or longitude. Of these, a total of 4.0%, or 54 community waters systems, were reported as in serious violation. It should be noted that the EPA is aware of a small number of water systems in Washington for which ECHO data may be inaccurate. However, since this is a small number and it is not listed as a ‘Primary Data Alert,’ we retain all states in this portion of the analysis. Finally, the EPA is generally aware that there are “inaccuracies and underreporting of some data in this system,” which is listed as a Primary Data Alert 27 . However, due to the lack of specifics, we cannot exclude inaccurate cases. Thus, our analysis should be viewed as reflecting drinking water quality is as reported by the EPA in August of 2020, which may reflect some level of inaccuracy.

Active Clean Water Act permittees were first identified by listed county. This was done because 345,176 out of 350,476 permittees had a county reported. Those without a county reported were located using latitude and longitude in the same manner as community water systems. There were 10 permittees without latitude and longitude or county listed which were excluded from our analysis. Of these, seven were in significant noncompliance and three were not. Due to some Clean Water Act permittees having latitude and longitude placements far away from the United States, those over 100 km from their nearest county were excluded from analysis. Unfortunately, ECHO data for the Clean Water Act data during the study period is inaccurate for 13 states. Although the nature of the inaccuracy varies from state to state, these issues generally stem from difficulties in transferring state data into the federal system. Due to this, these states appear to have far more permittees in Significant Noncompliance than are actually in violation. To address this issue, we removed all counties within these states from our Clean Water Act analysis. The impacted states include Iowa, Kansas, Michigan, Missouri, Nebraska, North Carolina, Ohio, Pennsylvania, Vermont, Washington, West Virginia, Wisconsin, and Wyoming 29 . Finally, for community water systems and Clean Water Act permittees, some counties (76 for community water systems and 5 for Clean Water Act permittees) had no reported cases. Those counties were treated as zeroes for cartography and as missing for modeling purposes.

Similar to prior work in this area 4 , 5 , 8 , we restrict our analysis to the scale of the county for reasons related to data limitations and resulting conceptual validity. Although counties are arguably larger in geographic area than ideal for an environmental injustice analysis, if we were to use a smaller unit for which data is available such as the census tract, the conceptual validity of the analysis would be limited due to the apolitical nature of these units. As outlined above, ECHO data is messy and missing many geographic identifiers. What is provided is generally either the county or latitude and longitude. If only the county is provided, then we are constrained to using the county regardless of conceptual validity. However, even when latitude and longitude are provided—which is the case for many observations—the provided point location says nothing about which households the water system or permittee serves or impacts. Due to this, whatever geographic unit we use carries the assumption that those in the unit could be plausibly impacted by the water system or permittee. Given that counties are often responsible for both regulating drinking water, as well as maintaining and providing water infrastructure 30 , we were comfortable with this assumption between point location and presumed spatial impact when using the scale of the county. However, we believe this assumption would have been invalid and untestable for smaller apolitical units for which demographic data is available such as census tracts.

Beyond the issues presented by ECHO data, the county is also the appropriate scale of analysis for this study due to the estimate-based nature of the ACS. ACS estimates are based on a rolling 5-year sample structure and often have very large margins of error. At the census tract level, these standard errors can be massive, especially in rural areas 31 , 32 , 33 . Due to this variation, and the need to include all rural areas in this analysis, the county, where the margins of error are considerably smaller, is the appropriate unit for this study. All of this said, the county is, in fact, a larger unit than often desired or used in environmental justice studies. Studies focused on exclusively urban areas with clearer pathways of impact can and should use smaller units such as census tracts. It will be imperative for future scholarship focused on water hardship across the rural-urban continuum to gain access to reliable data on sub-county political units, as well as data linking water systems to users, to continue documenting and pushing for water justice.

Dependent variables

The dependent variables for this analysis were assessed in both a continuous and dichotomous format. For descriptive results and mapping, continuous measures were used. For models of water injustice, a dichotomous measure which classified counties as either having low levels of the specific water issue or elevated levels of the specific water issue, was used due to the low relative frequency of water access and quality issues relative to the whole United States population. For all three outcomes, we benchmark an elevated level of the issue as what would be viewed as an unacceptable level under United Nations Sustainable Development Goal 6.1, which states, “by 2030 achieve universal and equitable access to safe and affordable drinking water for all” 1 . As this goal focuses on ensuring all people have safe water, we deem a county as having an elevated level of the issue if >1% of households, community water systems, or permittees had incomplete plumbing, were in Significant Violation, or Significant Noncompliance, respectively. Although we could have used an even stricter threshold given the SDG’s emphasis on ensuring access for all people, we use 1% as our cut-off due to its nominal value and ease of interpretation.

For water access, the continuous measure was the percent of households in a county with incomplete household plumbing as reported by the ACS. The ACS currently asks respondents if they have access to hot and cold water, a sink with a faucet, and a bath or shower. Up until 2016, the question also included a flush toilet 34 . As we must use the most recent 2014–2018 5-year estimates to establish full coverage of all counties, this means that incomplete plumbing in this item may, or may not include a flush toilet depending on when the specific county was sampled. The dichotomous version of this variable benchmarked elevated levels of incomplete plumbing as whether or not 1% or more of households in a county had incomplete plumbing.

Water quality was assessed via both community water systems from the Safe Drinking Water Act, and from permit data via the Clean Water Act. For Safe Drinking Water Act data, the continuous measure was the percent of community water systems within a county classified as a Safe Drinking Water Act Serious Violator at time of data extraction. The EPA assigns point values of either 1, 5, or 10 based upon the severity of violations of the Safe Drinking Water Act. A Serious Violator is one who has “an aggregate score of at least eleven points as a result of some combination of: unresolved more serious violations (such as maximum contaminant level violations related to acute contaminants), multiple violations (health-based, monitoring and reporting, public notification and/or other violations), and/or continuing violations” 27 . The dichotomous measure benchmarked elevated rates of Safe Drinking Water Act Significant Violation as whether or not >1% of county community water systems were classified as Serious Violators.

For Clean Water Act permit data, the continuous measure was the percent of permit holders listed as in Significant Noncompliance at the time of data extraction. Significant Noncompliance in the Clean Water Act refers to those permit holders who may pose a “more severe level of environmental threat” and is based upon both pollution levels and reporting compliance 27 . The dichotomous measure again set the threshold for elevated levels of poor water quality at whether or not >1% of Clean Water Act permittees in a county were listed as in Significant Noncompliance at time of data extraction.

Independent variables

The independent variables we include in models of water injustice are those frequently shown to be related to environmental injustice in the United States. These include age, income, poverty, race, ethnicity, education, and rurality 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 . Age was included as median age. Income was included as median household income. Poverty was the poverty rate of the county as determined by the official poverty measure of the United States 35 . Race and ethnicity was included as percent non-Latino/a Black, percent non-Latino/a indigenous, and percent Latino/a. Because the focus was on indigeneity, percent American Indian or Alaska Native was collapsed with Native Hawaiian or Other Pacific Islander. We did not include percent non-Latino/a white due to issues of multicollinearity. Finally, rurality was included as a three-category county indicator of metropolitan, non-metropolitan metropolitan-adjacent, and non-metropolitan remote, as determined by the Office of Management and Budget in 2010 36 . The OMB determines a county is metropolitan if it has a core urban area of 50,000 or more people, or is connected to a core metropolitan county by a 25% or greater share of commuting 36 . A non-metropolitan county is simply any county not classified as metropolitan. Non-metropolitan metropolitan adjacent counties are those which immediately border a metropolitan county, and non-metropolitan remote counties are those that do not.

Water injustice modeling approach

Water injustice was assessed by estimating linear probability models for the three dichotomous outcome variables with state fixed effects to control for the visible state level heterogeneity and differences in policy, reporting, and enforcement (e.g. the clear state boundary effects in Fig.  3 ). We employ the conventional Huber/White/Sandwich cluster-robust standard errors at the state level—which account for heteroskedasticity while also producing a consistent standard error estimate in-light of the lack of independence found between counties in the same state. All modeling was performed in Stata 16.0 and mapping was performed in QGIS 3.10. We assessed all full models for multicollinearity via condition index and VIF values and the independent variables had an acceptable condition index of 5.48 for incomplete plumbing and Safe Drinking Water Act models and 5.63 for Clean Water Act models, well below the conservative cut-off of 15, as well as VIF values of <10. We initially included percent non-Latino/a white as an independent variable, but removed the item due to unacceptably high condition index levels (>20). All indications of statistical significance are at the p  < 0.05 level and 95% confidence intervals and exact p -values of all estimates are provided in Supplementary Information. Each dependent variable was analyzed through a series of six models. First, we estimated separate purely descriptive models, where the only independent variables included were those associated with that specific dimension and the state fixed effects, for all five dimensions of environmental injustice. After estimating these five models, we estimated a full model including all social dimensions at once.

The reason for this approach was to ensure that we provided a robust descriptive understanding of the on-the-ground social patterns of water hardship, in addition to a full model showing the strongest social correlates of this issue. For example, if when we only included income variables we found that incomplete plumbing is less likely in counties with higher median incomes, but this effect goes away when we include other social variables, this does not remove the fact that there is an unequal distribution of incomplete plumbing by income on-the-ground. All that it means is that this income effect does not persist over and above the other social dimensions of environmental injustice. It may be that once other dimensions such as structural racism, captured by race and ethnicity variables, are considered, income is no longer a significant predictor. However, at a pure associational level, incomplete plumbing would still be unequally distributed by income on-the-ground. In fact, this is exactly what we find for incomplete plumbing (Supplementary Table  2 ). Due to this, both the pure descriptive and full models are needed for full understanding. Complete tables of all results are presented in the Supplementary Information File (Supplementary Tables  1 through 4 ).

Sensitivity tests

Due to our conservative approach to remove all problem states from the Clean Water Act portion of our analysis, we conducted a series of sensitivity tests wherein we generated national estimates of Significant Noncompliance, as well as models of elevated Significant Noncompliance under two scenarios (Supplementary Tables 5 and 6 ). In the first scenario we include all data reported by the EPA, meaning that we use all data for the 50 states, DC, and Puerto Rico, regardless of any EPA data flags. In the second scenario, we replaced the data lost when dropping states by duplicating the counties in the top and bottom 20% of significant violations in the remaining counties. The top and bottom 20% was chosen because the 945 counties removed when the 13 states were dropped was roughly equal to 40% of the remaining 2262 counties. This counterfactual allows us to get closer to a plausible estimate of the absolute scope of CWA Significant Noncompliance by adopting a scenario where the counties dropped in problem states were either very high, or very low in terms of Significant Noncompliance. Functionally, duplicating the bottom 20% posed a challenge because the bottom 30% of counties had zero permittees in Significant Noncompliance. This zero-bias is one of the primary reasons why our outcome variable was dichotomized. To address this, we randomly selected two-thirds of these counties for duplication using a seeded pseudorandom number generator in Stata. Following duplication of cases, all estimates and models were generated in the same manner as the primary models of this study.

Reporting summary

Further information on research design is available in the  Nature Research Reporting Summary linked to this article.

Data availability

The raw and geolocated datasets are publicly available on the Open Science Framework project for this study at https://doi.org/10.17605/OSF.IO/ZPQR9 ( https://osf.io/zpqr9/ ).

Code availability

Analysis code is available on the Open Science Framework project for this study at https://doi.org/10.17605/OSF.IO/ZPQR9 ( https://osf.io/zpqr9/ ). As the raw data was not geolocated using a code-based operation, code for this portion of the analysis is not available. However, the raw data is posted, and should researchers wish they will be able to use our description provided here to replicate geolocation using the GIS software of their choice. All other elements of the analysis are easily replicated via our provided code. As the both the raw and geolocated datasets are provided, replication of our analysis should be straightforward.

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Acknowledgements

The authors would like to acknowledge Tom Dietz, Lauren Mullenbach, Matthew Brooks, and Jan Beecher for their feedback on this manuscript. They would also like to thank Colleen Keltz at the Washington State Department of Ecology for alerting us to the issues with Clean Water Act data for Washington and other states.

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Mueller, J.T., Gasteyer, S. The widespread and unjust drinking water and clean water crisis in the United States. Nat Commun 12 , 3544 (2021). https://doi.org/10.1038/s41467-021-23898-z

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Climate Change, Water Quality and Water-Related Challenges: A Review with Focus on Pakistan

Toqeer ahmed.

1 Centre for Climate Research and Development, COMSATS University Islamabad, Park Road, Chak Shahzad, Islamabad 45550, Pakistan; [email protected]

Mohammad Zounemat-Kermani

2 Department of Water Engineering, Shahid Bahonar University of Kerman, Kerman 7616913439, Iran; [email protected]

Miklas Scholz

3 Division of Water Resources Engineering, Faculty of Engineering, Lund University, PO Box 118, 22100 Lund, Sweden

4 Department of Civil Engineering Science, School of Civil Engineering and the Built Environment, University of Johannesburg, Kingsway Campus, Aukland Park 2006, Johannesburg PO Box 524, South Africa

5 Civil Engineering Research Group, School of Computing, Science and Engineering, The University of Salford, Newton Building, Peel Park Campus, Salford M5 4WT, UK

Climate variability is heavily impacting human health all around the globe, in particular, on residents of developing countries. Impacts on surface water and groundwater resources and water-related illnesses are increasing, especially under changing climate scenarios such as diversity in rainfall patterns, increasing temperature, flash floods, severe droughts, heatwaves and heavy precipitation. Emerging water-related diseases such as dengue fever and chikungunya are reappearing and impacting on the life of the deprived; as such, the provision of safe water and health care is in great demand in developing countries to combat the spread of infectious diseases. Government, academia and private water bodies are conducting water quality surveys and providing health care facilities, but there is still a need to improve the present strategies concerning water treatment and management, as well as governance. In this review paper, climate change pattern and risks associated with water-related diseases in developing countries, with particular focus on Pakistan, and novel methods for controlling both waterborne and water-related diseases are discussed. This study is important for public health care, particularly in developing countries, for policy makers, and researchers working in the area of climate change, water quality and risk assessment.

1. Introduction

Climate variability involving changes in temperature, rainfall pattern and precipitation is increasing and heavily impacting on water resources, water-related diseases and, subsequently, human health, which is reliant on clean water. Water-related infectious diseases like malaria, dengue fever, chikungunya, along with their causative agents and the mode of transmission of these diseases have been affected by climate variability. Similarly, waterborne diseases like typhoid and cholera are influenced by climate change patterns, and subsequent risks related to these diseases are increasing [ 1 , 2 , 3 , 4 ]. About five cases of dengue develop into a hemorrhagic fever from 390 million dengue fever infections around the globe [ 5 ]. In order to save people from disaster, it has been suggested that poor and developing countries need to save, grow, invest, and protect poor and vulnerable people from economic crises [ 6 ]. Adaptation strategies related to these changes are important for policy and impact assessments [ 7 ].

Globally, almost all countries are affected by climate change impacts, particularly the developing countries, which are more vulnerable and prone to disasters like extreme floods, droughts, storms and heatwaves. In the last decade, a decline in economic growth has been observed in some developing countries, and people living in these countries are most affected as they do not have the resources to cope with the occurring natural disasters [ 8 , 9 ]. Half of the world’s poor population lives in Sub-Saharan Africa. Significant poverty reductions have been observed in East Asia, especially China and Indonesia, between 2012 and 2013 [ 6 ]. However, developing countries are still suffering from economic problems, especially people living in rural agricultural areas with no access to essential resources in order to gain education [ 6 , 10 ].

Roser and Ortiz-Ospina [ 11 ] reported that people earning less than 3.10 US $/day (less than Pak Rs (PKR). 500) mostly live in countries such as Pakistan, India, Bangladesh and Ethiopia. Poor people are more vulnerable to natural disasters. Pakistan is at number 7 in a list of endangered countries, with 70% of its population exposed to natural hazards [ 12 ]. Millions of people in India and Bangladesh are exposed to floods. Due to climate variability, even developed countries like Japan, Hong Kong and Taiwan have been exposed to at least one type of natural hazard in the past few years. The global Climate Risk Index indicates the extent of vulnerability of a country from weather-related events like flooding, drought, heat waves and storms [ 13 ]. A low climate risk index (CRI) value indicates the highest vulnerability as some countries are more prone to frequent disaster. Of the top ten most affected countries by natural disasters, nine were from developing countries with low-middle-income, all except for Thailand ( Table 1 ). Among them, Serbia, Afghanistan and Bosnia and Herzegovina were the most affected [ 14 ]. Pakistan and the Philippines are affected recurrently by catastrophes. They are commonly ranked among the most affected countries. According to CRI 2018, the Philippines are the second most affected country among the top ten climate change-affected countries. The CRI [ 10 ] indicated that Pakistan was at number eight in the list of most affected countries between 1995 and 2014 ( Table 1 ) [ 10 ].

The list of the top 10 countries most affected in the Climate Risk Index (CRI; annual averages; adopted from [ 14 ]) between 1995 and 2014.

More than 2.5 billion individuals (30% of the world’s residents) are at risk of dengue fever, particularly in Southeast Asia, the Americas, and the Western Pacific. According to the UN water report [ 15 ], world water demand will increase by up to 55% by 2050 due to more demand by industry, domestic consumption, food production and electric generation use. Similarly, global demand for food will increase by 60% (100% in the developing countries) by 2050 due to an increase in population [ 15 ]. Stress on sustainable water management will increase due to poverty, unequal distribution of resources, inequitable access to resources and poor management.

The current situation indicates that mitigation and improved adaptation strategies are required to minimize the impacts of climate variability. This study analyzes recent scenarios impacted on by population increase, water-related disasters, water pollution and how to control diseases linked to water. The main objectives of this paper are to analyze climate variability and water-related disasters as well as their impacts on human health. Finally, some key recommendations are made for policy-makers.

2. Methodology and Review

2.1. literature selection.

In this study, the authors assessed peer reviewed research papers, reports and grey literature published after 1979. Websites including google scholar ( https://scholar.google.com.pk ), Web of Knowledge ( http://isiknowledge.com ), ScienceDirect ( http://www.sciencedirect.com ) and Scopus ( https://www.scopus.com ) were searched for relevant literature. More attention has been paid to recent but already well-referenced literature. Relevant literature was selected based predominantly on the following inclusion criteria: (a) peer-reviewed research papers published by impact factor-listed research journals; (b) peer-reviewed scientific reports from world-known publishers; (c) literature was screened by using keywords (climate variability; climate and water quality; waterborne; water-related disease; dengue fever and health impacts; Zika virus; Chikungunya; method for controlling waterborne diseases; temperature and precipitation effects; developing countries; population and water quality; climate change impacts on chemical water quality; water quality in Pakistan; water governance; water management; and water pollution); and (d) preference was given to studies published in English language.

2.2. Climate Variability

Climate variability is a growing concern worldwide [ 16 ]. Climate change deeply impacts on social and natural environments and is one of the major threats to public health [ 17 , 18 ]. The water quality of recreational waterbodies such as coastal waters is considerably affected by extreme weather conditions like storms and typhoons, which increase the contamination of drinking water leading to water-borne diseases [ 19 ].

Changes in climate have varied greatly and influenced water resources, groundwater contamination, health and subsequently human life [ 20 , 21 ]. High uncertainty regarding expected changes in temperature and rainfall in the upcoming years has been reported in some studies [ 22 ]. It has been estimated that the average global temperature for the last hundred years has increased overall by approximately 0.8 °C due to the emission of greenhouse gases, and recent years were announced as the hottest in recent history. Due to the increase in global temperature, changes in precipitation levels have not been uniform in recent decades. As a result, monsoon rainfalls are more likely to happen in humid and sub-humid areas, whereas there will be a decrease in winter and summer rainfalls in coastal and hyper-arid areas. Besides, it has been claimed that sea levels will rise to a range of 1 to 3 mm per year [ 23 , 24 ]. There is also uncertainty about rainfalls with uneven temporal and spatial distribution, and longer dry spells evoking drought conditions [ 25 ].

Indeed, due to human activities, the mean temperature on the surface of the earth has been increasing over the past century [ 26 ]. It has been estimated that hot summer days have also become more extended and regular in some parts of the globe. Increased surface temperature is leading to an increase in evaporation from the oceans and land. Accordingly, there will be an increase in global average precipitation. Some regions also experience droughts due to high evaporation levels and shifting of wind patterns while some parts of the world receive flash floods. However, it is very difficult to differentiate whether an extreme weather event is caused by natural or human influences [ 27 ]. In a study by Levy et al. [ 28 ], the general effects of climate change on water-borne diseases have been investigated. Other studies have focused on specific components of climate change such as the impact of short-term extreme flood events on infectious diseases [ 20 , 29 ].

Global warming causes the temperature to rise and, as a result, low-level glaciers are melting [ 30 ]. About 76 lakes covering an average area of 545 ha in high mountainous regions were studied. Regular monitoring of glaciers was recommended to support water management in the context of climate variability [ 31 ]. Temperature may increase this century by 2%–6 °C, which will particularly impact negatively on water resources in Central Asia which depend commonly on river water for agriculture [ 32 ].

Glaciers are one of the most important sources of water for Asian countries. About 41% of the area of glaciers are vulnerable to climate change in China [ 33 ]. Climate change is linked to an increase in mean temperature [ 23 ] and is the main factor in the melting of glaciers [ 34 ]. This has also led to changes in precipitation pattern, diversity and rate. Since 1900, changes in precipitation patterns amounted to an approximately 2% increase over the land area of the globe [ 35 , 36 ]. Likewise, a correlation between the increase in streamflow and precipitation has been identified [ 37 , 38 , 39 ].

It was reported that roughly 80% of diseases in developing countries such as Pakistan are related to waterborne diseases [ 40 ]. In Pakistan, water quality is being impacted by climate change through temperature and rainfall fluctuations [ 41 ]. A study showed that the maximum temperature has significantly augmented (in over 30% of sites) during the pre-monsoon season annually [ 42 ]. A considerable increase was observed in March. The minimum temperature showed positive trends for the pre-monsoon season at the annual scale. There was a cooling trend in the northern areas during the study period. The maximum temperature increased faster than the minimum temperature in the northern areas during all seasons studied and at annual resolution, while the opposite occurred for the rest of the country (except during the pre-monsoon season). It has been estimated that the highest correlation coefficients between patterns and both minimum and maximum temperatures were observed in the months of the pre-monsoon season [ 43 ].

2.3. Water Pollution, Population and Water Quality

The world population is expanding, with a total of 7.4 billion in 2016, and is expected to increase in the upcoming decades [ 44 ]. The eight most populous countries have a combined population of over 4.054 billion, which is expected to increase to 4.980 billion by 2050 ( Table 2 ). With this increase in population, water resources are under stress, especially in the developing countries.

Eight most populous countries in 2016 and their prospective population by 2050 (adapted from [ 44 , 46 ]).

Water pollution is directly related to population growth and has a direct impact on human health. Population growth and anthropogenic activities heavily influence water resources. The demand for water is augmented along with an increase of population, and ultimately the quality of water resources will be affected [ 45 ]. According to data for the world’s most water-stressed countries [ 46 ], Pakistan is among the most vulnerable, and will become a water-stressed country by 2040 [ 47 , 48 ].

According to Vineis et al. [ 49 ], about 884 million people are living without access to clean drinking water in 2019. Poor quality of water, especially drinking water, increases the chances of waterborne diseases [ 40 ]. About 1.8 million people die every year due to cholera and diarrhea, and 3900 children die every day due to poor water and sanitation conditions [ 50 ]. Similarly, more than one billion people lack access to improved drinking water, particularly those living in Asia [ 51 ]. In developing countries, the population is increasing, and cities will be overpopulated in the next 20 years. Accordingly, demand for improved water resources management, water quality control and enhanced flood and drought management will increase [ 52 ].

As reported by the WHO [ 53 ], half of the world’s population will suffer water stress conditions by 2025. Similarly, along with water shortage, water quality is also negatively affected, so that 1.8 billion people around the world are obliged to consume water contaminated by sewerage for drinking, which practice transfers diseases like cholera, typhoid, dysentery and polio. Empirical studies have already indicated the downside effects on human health of pollution and poor water quality due to the rapid increase in population and urbanization [ 54 ]. Regions or countries facing climate challenges and natural disasters such as drought and floods have also to endure population growth problems, and inevitably anthropogenic activities alter water systems [ 55 ]. A decrease in water resources due to less income and slow development will increase the problems of water quality and health issues. Water availability has been decreasing in all sectors by 7–11% during the last two decades [ 41 ]. Water availability is affected by climate change as well as water governance and management issues. There is a need to increase water storage capacity and installation of water retention wells for groundwater recharge. Groundwater regulations have been approved by all provinces of Pakistan except for Sindh, but implementation of polices in the true sense are lacking. By area, Sindh is the third largest province of Pakistan and by population the second largest. This is important as Karachi city (the former capital) is the largest city of Sindh province. Incentives should be implemented for the general public to obey governmental rules for water saving and fines imposed on violators. The government should implement licensing for the installation of new bore wells and there should be a record of the number of tube and bore wells installed, as no such data exist especially for private bore wells.

Water quality is linked with water availability. Water quality analysis of the major cities of Pakistan has been recently completed by the government. Similarly, other research and development organizations and non-governmental organizations (NGO) are performing water quality analysis especially in rural areas. Bacteriological water quality is often more important than chemical water quality as water resources are contaminated with fecal matter. No data on gastroenteritis have been found in allied hospitals when asked for records of patients suffering from food or waterborne diseases. It is strongly recommended in hospitals that records of people suffering from waterborne diseases are maintained.

2.4. Climate, Water-Related Diseases, and Health Impacts

Climate variability effects climate-sensitive diseases like dengue fever, diarrhea and cholera [ 56 , 57 , 58 , 59 ]. Microclimatic parameters, especially precipitation and temperature, play a key role in spreading waterborne and water-related diseases [ 60 , 61 , 62 , 63 , 64 ]. Microbiological, bioinformatics and genomic tools have provided some evidence that El Niño is the main key element in triggering long distance spread of cholera [ 65 ]. Climate change has a direct effect on the reemergence of waterborne infectious diseases such as cholera [ 66 ]. It is expected that diarrhea rates will be aggravated in many developing countries due to changes in climate, but the extent will vary depending on the nature of change, region and local climate [ 67 , 68 ]. A direct relation has been observed between climate-related disasters such as floods, heavy rainfalls and waterborne diseases. Typically, waterborne diseases and zoonotic infections increase after floods and rainfall, and high temperature also supports the growth of waterborne diseases [ 69 ]. There is a correlation between waterborne diseases and wet summer and humid weather. Typhoid is linked to dry weather in Europe [ 70 ]. Climate change could also pose an increased health risk linked to pathogens like Campylobacter, Cryptosporidium and norovirus. Norovirus and Cryptosporidium are less temperature-sensitive and are more resilient than Campylobacter [ 71 ]. Legionella species are ubiquitous in natural settings, share common habitat with human beings and transfer to humans, causing infection on exposure. Rainfall may cause exposure to Legionella infections and lead to the corresponding disease called Legionellosis [ 72 ]. Multiple studies have been devoted to infections related to contaminated water [ 73 ]. Similarly, drought can aggravate the effluent concentration runoff, pH and chemical quality. Contamination of surface water puts treatment plants at risk, leading to poor drinking water quality, which is especially detrimental for the elderly [ 74 ]. Likewise, rainfall and floods may increase waterborne diseases. A study conducted in Vietnam linked the impact of floods to dengue, pink fever, skin problems like dermatitis, and related psychological impacts [ 75 ].

According to the WHO, “Emerging pathogens are defined as pathogens seemed to have existence in a human population for the first time, or previously but are growing in frequency into areas where they have not been reported previously, generally over the last 20 years” [ 76 ]. According to this criterion, 96 genera containing 175 species are considered to be emerging pathogens. Other than common waterborne pathogens, Helminths, Giardia lamblia, Entamoeba histolytica , Legionella, Cryptosporidium, H. pylori, E. coli O157 and viruses like norovirus, hepatitis E virus and rotavirus have been confirmed as emerging pathogens that may spread through water [ 54 , 55 , 56 , 57 , 58 , 59 , 60 , 61 , 62 , 63 , 64 , 65 , 66 , 67 ]. These pathogens spread through changes in climate such as change in rainfall and global weather pattern, and deterioration in the ozone layer along with the destruction associated with UV light [ 54 ]. Different aspects of climate change including rising sea levels, flooding, extreme rainfall and rising temperature have previously been assessed in terms of their transmission and spread of water-borne diseases such as cholera and malaria [ 77 ].

In developing countries like Pakistan, the literacy rate is low, especially in rural areas, and people have no awareness about water quality, waterborne diseases and water pollution. People are using the same water for drinking and agriculture purposes. There is a direct relationship between education, income and awareness about water pollution, waterborne diseases and health impacts. According to a survey, individuals with higher levels of education are well-aware of the consequences of waterborne diseases [ 78 ]. It is worth mentioning that diseases linked to the marine and water ecosystems can be caused by waterborne pathogens, as these microbes are naturally present in different settings.

This literature review shows that there is a research gap in studies that deal with waterborne diseases and climate variability, and, therefore, more research is needed to specifically explore the impacts of climate change on waterborne diseases. Figure 1 represents some of the most important factors regarding climate change-related health impacts on human beings.

Health impacts of climate change (adapted from [ 79 ]).

2.5. Climate Impacts on Chemical Water Quality, Water-Related Diseases, and Health Perspectives

Climate change has significant impacts on chemical water quality when compared to changes in meteorological parameters [ 80 ]. Storm, snowmelt, drought and elevated air temperature have a significant impact on drinking water quality [ 81 ]. For instance, heavy rainfall can increase the turbidity of water resources. Similarly, an imbalance in chemical water quality has been observed due to a rise in temperature [ 82 ]. Chlorine used for decontamination of water may produce more trihalomethanes after reaction with organic acids at high temperature [ 83 ]. As stated earlier, average temperature has been increasing due to global warming, and this can impact on water resources including chemical water quality. Similarly, dissolution of chemicals, especially agriculture waste and fertilizers, can change the quality of water resources. According to Quevauviller and Umezawa [ 84 ], climate change may impact on water chemistry and sea-level rise, so salinization may be affected, which influences the depletion of freshwater and river environments. Different factors like acidification and remobilization of contaminants in sediments due to flooding and an increase in temperature can modify pollutants in water resources, which can affect aquatic life [ 85 ]. A study conducted in the Mekong Delta on climate change impacts on water-related diseases reported that limited work has been done on the relationship of climate change impacts on water quality [ 86 ].

Due to the effects of climate change, the salinization of drinking water has introduced problems for low income countries [ 49 ]. For example, salt intrusion and related health issues are common in Bangladesh [ 87 ]. Approximately 20 million people are at risk of hypertension in Bangladesh, which is a major cause of cardiovascular diseases [ 88 , 89 ], since more salt in water can cause hypertension and associated diseases. A study conducted in Bangladesh using an integrated salinity flux model and hydrodynamic model reported that both salinity and intrusion length has increased in the Gorai river due to the sea-level rise [ 90 ]. A similar study investigated the effects of saline contamination in drinking water on human health hazards in Bangladesh [ 91 ]. Another study reported high levels of arsenic in surface water and 2–4 times the amount, in drinking water in Bangladesh, with respect to the average eligible standards [ 92 ]. The problem of salinity and hypertension will be exacerbated in the future among people living in coastal areas due to the high intake of sodium through drinking water [ 93 , 94 ].

In another study conducted in Beijing, China, post-flood water quality was reported to have quality samples unfit for drinking purposes [ 95 ]. Indeed, both floods and drought conditions deteriorate the chemical quality of water, which leads to significant health impacts and high risks for consumers ( Table 3 ).

Potential health impacts of major physico-chemical contaminants in developing countries including Pakistan.

According to the Intergovernmental Panel on Climate Change (IPCC) Fourth Assessment Report (AR4) Climate Change [ 103 ], climate change-related amendment can affect diseases caused by water, which are categorized as waterborne, water-related, water-washed and water-based. The main considerations proposed in AR4 in order to find the relationship between climate change, water quality and water availability are below:

• 1. The linkage between water availability, access to improved water, and health burden due to diarrheal diseases;
• 2. The role of rainfall in waterborne disease outbreaks through water supply;
• 3. The effect of temperature both on chemical and biological water quality; and
• 4. The direct effect of increased temperature on diarrheal diseases.

It has been reported that climate change can affect water-related diseases like malaria, dengue fever, and other infectious diseases. According to Rogers [ 104 ], one-third of the global population lives in places linked to dengue transmission. Similarly, malaria is a rainfall-dependent disease and decreases with reductions in rainfall.

2.6. Elucidation to Diminish Water-Related Issues

Numerous methods and remedies have been used to control mosquito-related diseases, and the best of these is to control the existence of mosquitoes, which involves chemical, biological, environmental management, personal protective measures and physical methods [ 105 ]. Chemical methods include the use of tested and recommended insecticides, e.g., pyrethroids for killing adults and larvae. These should be used under the supervision of experts and trained staff such as a team of entomologists, a vector control supervisor and field staff [ 106 ].

Direct chemical spraying or aerial spraying of chemicals by low flying aircraft (to cover a large area or when there is limited access by vehicles) should be accomplished at the habitats, resting sites and breeding places of the target insects at regular intervals of 2–3 weeks. In-house spraying should also be done in all bedrooms, washrooms, wall corners, etc. For dengue control, man-made habitats should be screened, and Methoperene/Altosid (Briquets) and Diflubenzuron (Dimlin) should be applied.

As reported by Yi et al. [ 107 ], diesel oil is effective in killing larvae and pupae of mosquitoes in small waterbodies, but this can also kill other aquatic animals and is unsustainable. They suggested golden bear oil as an alternative, but this product is only available in the USA. They also suggested various methods to control mosquitoes using mosquito traps, genetically modified male mosquitoes and mosquito counter devices. Furthermore, indoor fogging or space spraying is an effective way to control dengue [ 108 ]. Larvicides should be applied on clean and stagnant water.

Multi-purpose environmental management of marshes, open drains, standing water in open fields, surface water, gardens and waste is required for disease control. Personal protection measures include personal protective clothing, bed nets (long lasting insecticide treated nets and curtains at doors), use of gauze on doors, and insect repellent lotions. Picaridin/Icaradine and N,N-diethyl-meta-toluamide (also called DEET) are recommended repellents that can be used in emergency cases. Cloth can be treated with permethrin to control mosquitoes, at the recommended dose of 1.25 mg/m 2 after every five washes. Even simple physical methods such as closing doors, especially in the morning and evening, have a positive impact on preventing diseases. Rapid population growth and urbanization, especially encroachments, provide ideal places for breeding of mosquitoes. In the absence of medicine and therapy, it is better to control this growth and breeding of mosquitoes and other vector-spreading microbes [ 109 , 110 , 111 ].

Concerning the environmental consequences of changing climate, more attention is required from experts, authorities and health departments on preventing the spreading of lethal diseases such as dengue and malaria. It is advisable that malaria and dengue control programs should be a part of national health policy with strong resource commitment and implementation. Increasing awareness and educating society is a vital element to cope with spreading of waterborne diseases (e.g., dengue fever). These programs can be started by educational institutions, offices, meetings, community reunions, etc. Besides, cleaning at household level with detergents, insecticides and other surface cleaning agents is highly recommended. Media can also play an important role in enhancing awareness through newspapers, TV programs, talk shows, etc. Likewise, a reduction of breeding sources of mosquitos and the introduction of waste management campaigns are important at community level. Indeed, health protection campaigns should be the top priority.

According to the literature, people in South Africa spent about eight hours daily in fetching water and only 19% treat their water before use. Government subsidies on water treatment chemicals and fuels for boiling water may help in increasing the percentage of people treating their drinking water and reducing waterborne diseases [ 112 ]. Regarding improving water quality, both adaptation and mitigation measures are required. In this respect, infrastructure improvements, reduction of pipe leakage, introduction of advanced water purification systems, and direct supply of clean water are necessary for the provision of safe drinking water [ 82 ]. During periods of flooding, water treatment is of great importance in controlling waterborne diseases [ 113 ]. Other interventions and home water treatments including chlorination and UV treatment [ 114 ]. There is a strong need to establish new sustainable development policies to preserve water. Without inaugurating new policies, around 40% of the world’s population is projected to experience severe water stress by 2050, especially in Africa and Asia, where the population is projected to increase from 7 billion to over 9 billion by 2050 [ 115 ].

3. Pakistan’s Perspective, the Status Quo

3.1. water quality issues.

Based on the long-term CRI, Pakistan was the fifth most affected country in the world during the period between 1999 and 2018 [ 116 ]. Moreover, Pakistan severely suffers from water shortage and lack of clean drinking water [ 85 ]. In general, just 20% of the country’s residents have access to clean potable water, which makes the remaining 80% dependent on polluted and unhealthy drinking water [ 117 , 118 ]. Many empirical studies have been conducted on water quality issues in Pakistan, but some important studies on biological and chemical water quality conducted in different cities across all the provinces of Pakistan have reported on the deterioration of water quality throughout Pakistan and highlighted an increase in waterborne bacterial and other related diseases ( Table 4 ). The lack of access to safe drinking water causes waterborne diseases, which constitute about 33% of all deaths [ 118 ]. Another study reported that between 20% and 40% of all diseases in Pakistan are due to poor quality of water [ 119 ]. This can be explained by deficiencies in waste management, lack of protection of water resources, poor sanitation, adverse anthropogenic activities and lack of social awareness [ 120 ]. A general analysis of water quality data indicates the poor circumstances of water resources in Pakistan ( Table 4 ), highlighting the need for new water treatment policies. Roughly 60 million Pakistani residents are affected by high levels of arsenic in their drinking water [ 121 ]. Rural areas are more vulnerable in terms of access to safe drinking water compared to major cities or the capital city. A study of the Tehsil of Jehlum district found more than 80% contaminated water [ 122 ]. Even water supplied to schools was poor in terms of drinking quality [ 123 ]. It is worth noting that Pakistan mainly relies on the Indus River as one of the main surface water resources. However, climate change has been negatively impacting on the Indus River, which has increased the pressure on sustainable water resources [ 124 ]. A 50% reduction of the flow rate of the Indus River would have a detrimental impact on public health, environmental protection and public finances [ 125 ]. Similar consequences can be envisaged for other developing countries like Ethiopia, where major rivers have faced decreases in both water quality and quantity [ 126 ].

Water quality situation in different provinces of Pakistan and associated impacts on the parameters studied.

Clean and healthy drinking water has a high impact on recreational activities, fisheries, tourism and sports. However, potable water resources can become polluted, which negatively impacts on both economic and health aspects [ 126 ]. According to reports by the Pakistan Council of Research in Water Resources, a survey was conducted in 23 major cities of Pakistan; four major contaminants prevailed in Pakistan; most contaminants were of bacterial nature (69%). This was followed by arsenic (24%), nitrate (14%) and fluoride (5%) [ 167 ]. According to the report, 69% of sources were contaminated according to the National Standards for Drinking Water Quality. According to a Khyber Pakhtunkhwa (KP) health survey, in 2017 89% of households had access to improved drinking water. This is similar to the 94% figure regarding Punjab province as reported by the Punjab Government [ 168 ]. Efforts have been made by the Punjab Government to provide clean and contaminant-free water. For example, some important projects including the Punjab Saaf Pani (PSP) project, worth 70 billion PKR (1 US $ = 158 PKR), have been launched to provide clean drinking water to poor urban and rural areas. For 2015–2016, 11 billion PKR were allocated for medium-term development goals. The PSP is designed to provide 3 L of clean drinking water per capita as part of the approved plan. The program promotes the installation of filtration plants, new water supply schemes and rehabilitation of existing schemes. Water treatment plants have been installed in Bahawalpur, Bahawalnagar, Lodhran and Rahimyar to supply safe and clean water to these cities.

Pakistan’s gross domestic product in 2018 was 314.6 billion US $. A project entitled “Changa Pani Programme” was launched to maintain sanitation schemes and provide rural water supply. A total of PKR 1 billion have been allocated for this program. Sustainable operation and maintenance mechanisms of rural water supply schemes are another initiative running in Punjab. Under this scheme, 199 dysfunctional water supply systems have been identified, while an initiative has been taken to rehabilitate 135 rural water supply schemes in Rajanpur, Chakwal, Vehari and DG Khan with the assistance of UNICEF. Similarly, in the 2020–2021 budget, PKR 6 billion were spent on clean drinking water (Punjab Aab-e-Pak Authority) and PKR 3.29 billion on water supply and sanitation [ 169 ]. For KP, 18.6 PKR billion were invested in the water sector [ 170 ]. For Sindh province, PKR 19.3 billion were spent on water supply and sanitation, while PKR 39 billion were invested on water supply and sanitation schemes including 398 projects in 2019–2020. PKR 1.94 billion were spent by Karachi city [ 171 ]. For Azad Jammu and Kashmir (AJK), PKR 700 million were invested on water use charges schemes and PKR 540 million on none-specified water categories. Similarly, GB and Balochistan did not specify water investments, but overall allocations for development work have been recorded. More initiatives and fair use of budgets for clean drinking water and water supply schemes are required in other provinces of Pakistan to fulfill the demand for clean drinking water, and to reduce waterborne diseases.

No specified data have been found on waterborne diseases in hospitals. However, dengue-related data are available, as surveillance teams of public health departments along with the government are monitoring dengue-related cases. It is highly recommended that patients are registered as suffering from, for example, gastroenteritis or shigellosis for proper monitoring at the national level. Typhoid, abdominal cramps and diarrhea are the most common water- and food-related illnesses; the number of patients varies from district to district in each province, but without registration it is very difficult to find and distinguish patients suffering from different specific diseases.

3.2. Water Governance and Sustainability

Water availability and linked water quality are being heavily impacted upon by climate change throughout the world, especially in Pakistan. Changes in rainfall patterns, shifting of seasons, increase in temperature, droughts, heatwaves and storms are affecting water resources. Demand for water is increasing due to an increase in population, urbanization and industrialization. It is important to manage the existing water resources. In order to achieve Sustainable Development Goal 6, ensuring availability and sustainable management of water sanitation for all, water governance is essential.

Water governance is concerned with the social, economic, administrative and political organization that influences the use of water and its management. It is important to discuss the management of water, rights to water, service provider roles and allied beneficiaries. Water governance discusses the formulation and implementation of water policies, legislation, the role of institutions, civil society and the general public in relation to provision of services and water usage.

A Pakistani national water policy has been approved in April 2018 and the water act has been implemented in almost all provinces except Sindh Province. Lack of coordination among the institutions as well as capacity building and funding constraints are important challenges to be addressed. Equity and social balance are important in addressing water governance-related issues. There are opportunities to address these issues with, for example, IT-based monitoring systems for dealing with accountability and water theft. Public–private partnerships are important in tackling water-related challenges. A good example is the water metering and pricing program of Bhalwal City in the Sargodha District of Punjab Province, where authorities have successfully implemented 24/7 supply of safe drinking water. Similarly, smart water metering has been installed in one of the sectors, named I-8, of Islamabad for the said initiative. (In Islamabad, different sectors are named alphabetically). International collaboration can help in capacity building and knowledge sharing. Awareness regarding water conservation and strategies to conserve water at all levels is necessary to save water. The inclusion of information on climate change and water conservation in the educational curricula at all levels is recommended. Fines should be imposed on violators and incentives should be given to the general public by the water authorities for water conservation and for following water laws. These kinds of initiative can help in water governance and sustainability in the future.

4. Conclusions and Recommendations

This literature review indicates that global warming has led to an increase in the average temperature around the globe, which has been heavily impacting on water resources, especially in Africa and Asia, as agriculture is mostly dependent on river water flow. Several developing Asian countries have already encountered the consequences of water stress. Hence, river water monitoring is an essential requirement, especially due to the impacts of climate change such as glacier melting, rainstorms and droughts.

Increases in population and anthropogenic activities have heavily influenced water resources and increased water pollution. Indeed, various studies have reported that water pollution has increased in the last decades, and consequently water-related diseases influence the health of many citizens in developing countries. The following are important recommendations which can be helpful in coping with the consequences of climate change in terms of water-related challenges:

• Due to the shift in seasons, in some locations as a result of climate variability, new water resources (e.g., melting glaciers) have been emerging. However, there is a need to manage and store water for present and future use. For instance, watershed management with dam systems might alleviate drought and floods.
• Developing effective treatment methods e.g., [ 172 , 173 , 174 ], for addressing the sixth United Nations sustainable development goal, which deals with fecal contamination (69% fecal pollution has been reported in 23 major cities) and provision of safe drinking water to the general public.
• Adaptation strategies such as protection of water resources and watershed management should be adopted to cope with unforeseen situations and to decrease the water-related disease burden.
• Education and social awareness play a major role in confronting and controlling water pollution, waterborne, and water-related diseases, and subsequently in improving human health in developing countries.

These recommendations are also valid for many other countries with similar challenges to Pakistan.

Acknowledgments

The authors gratefully acknowledge the support received from Centre for Climate Research and Development (CCRD), COMSATS University Islamabad, for providing resources and funding the under COMSATS Research Grant Program No. 16-59/CRGP//CIIT/ISB/17/1092.

Author Contributions

Conceptualization, T.A., M.Z.-K. and M.S.; methodology, T.A.; investigation, T.A., M.Z.-K. and M.S.; writing—original draft preparation, T.A; writing—review and editing, M.Z.-K. and M.S.; visualization, T.A. All authors have read and agreed to the published version of the manuscript.

Gratefully acknowledge the support received from COMSATS University Islamabad under the grant No. 16-59/CRGP//CIIT/ISB/17/1092.

Conflicts of Interest

The authors declare no conflict of interest.

Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations.

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Open Access

Improve water quality through meaningful, not just any, citizen science

* E-mail: [email protected]

Affiliation Rathenau Instituut, Royal Netherlands Academy of Arts and Sciences, The Hague, The Netherlands

Affiliation HU University of Applied Sciences Utrecht, Utrecht, The Netherlands

• Anne-Floor M. Schölvinck, 
• Wout Scholten, 
• Paul J. M. Diederen

Published: December 7, 2022

• https://doi.org/10.1371/journal.pwat.0000065
• Reader Comments

Citation: Schölvinck A-FM, Scholten W, Diederen PJM (2022) Improve water quality through meaningful, not just any, citizen science. PLOS Water 1(12): e0000065. https://doi.org/10.1371/journal.pwat.0000065

Editor: Debora Walker, PLOS: Public Library of Science, UNITED STATES

Copyright: © 2022 Schölvinck et al. This is an open access article distributed under the terms of the Creative Commons Attribution License , which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Funding: The authors received no specific funding for this work.

Competing interests: The authors have declared that no competing interests exist.

Water pollution is an urgent and complex problem worldwide, with many dire consequences for ecosystems, human health and economic development. Although policy measures in OECD countries have helped to reduce point source pollution, the situation is set to worsen: population growth and climate change are placing increasing pressures on the ability of water bodies to process wastewater, nutrients and contaminants [ 1 ].

For future generations to maintain a sufficient supply of clean drinking water and to retain a vital level of biodiversity, it is critical to involve the general public in dealing with the problems of water quality and water pollution. One specifically important and increasingly prominent way for the general public to get acquainted with water quality issues is through participation in research projects. All around the world numerous citizen science (CS) projects take place in the field of (drinking) water quality, hydrology, groundwater levels, and water biology [ 2 ]. In most cases these projects are motivated by the enormous potential volunteering citizens have to increase the temporal and spatial data availability. We argue that the value of many CS projects lies beyond data availability, in the broader societal benefits that these projects aspire or claim to achieve. In turn, these benefits could improve the way we approach water quality issues. The list of claimed and potential benefits is long: raising awareness, democratisation of science, development of mutual trust, confidence, and respect between scientists, authorities and the public, increased knowledge and scientific literacy, social learning, incorporation of local, traditional and indigenous knowledge, increased social capital, citizen empowerment, behavioural change, improved environment, health and livelihoods, and finally motivational benefits [ 3 ].

Many of these broader societal benefits of public engagement with water research are especially important to battle water related issues worldwide. Increased ‘water awareness’ among the public is needed to encourage a general sense of urgency and hence support for research investments and policy measures. In the Netherlands, like in many other countries, many citizens take safe and clean (drinking) water for granted [ 4 ]. Therefore, people are not sufficiently aware what investments are needed to provide safe tap water and what they themselves should do to reduce domestic water pollution. To truly counter the dangers of deteriorating water quality, water science and policy must be organised more inclusively and democratically.

The potential societal effect of CS in the water quality sector is substantial. In the Netherlands alone, more than 100,000 citizens volunteer as ‘sensors’ or observers in the numerous nature oriented research projects, in which they, for example, count aquatic animals or measure the chemical composition of river water. These projects are generally low-threshold, because the research tasks are relatively simple and adapted to the limited expertise and research skills of the participants. The large-scale and long-term monitoring done by volunteers would be unaffordable if carried out by professionals [ 5 ]. In other CS projects, though smaller in quantity, citizens have a larger degree of control. This is a gradual difference, typically divided in four categories, ranging from contributory (lowest level of control) to collaborative, co-creative and finally collegial [ 6 ]. Alternatively, these levels have been designated crowdsourcing, distributed intelligence, participatory science and extreme citizen science [ 7 ]. We consider all these levels of control as participating in research, even when the volunteers merely function as observers.

Although the potential benefits of citizen involvement with research projects are numerous and the potential societal impact is high, there are two main obstacles that must be overcome. First, the actual effects of these types of projects, other than the well-reported scientific benefits, remain largely unknown [ 3 , 8 , 9 ]. Do participants have an increased understanding of the concerns of water quality researchers? Do they flush fewer medicines down the toilet? Do they avoid using pesticides in their gardens? Moreover, in order to truly raise public awareness and support for policies addressing water quality, it is important to not only get people involved who are already interested in nature, water quality and/or scientific research. The challenge is to have a diverse group of participants and to involve hard-to-reach groups [ 10 ].

Second, the dominant picture of CS projects, in our own Dutch based study as well as all across the world [ 3 ], is that most citizens participate in the collection of research data. Recalling Shirk et al.’s typology of involvement [ 6 ], this can be considered the lowest level of control and participation. Researchers, policy makers and interest groups hope that this type of involvement will generate public support for more scientific research and more effective policy measures to improve water quality, but citizens performing more significant roles in the research process is still uncommon.

From our analysis, we draw three recommendations to overcome these obstacles and to move beyond CS in water research for the sake of research only, in order to make it more meaningful in a broader, societal sense. For a start, we recommend to thoroughly evaluate the effect of citizen science on the attitudes , behaviour and knowledge of participants and on the system as a whole . As mentioned above, and also pointed out by Somerwill & Wehn [ 9 ], ‘the exact impacts of citizen science are still to be fully and comprehensively understood, while up to date impact assessment methods and frameworks are not yet fully integrated in practice’. Since the potential and claimed benefits are substantial, there is a considerable responsibility to prove these effects and to improve CS project designs to stimulate the occurrence of these benefits. Recent work provides the necessary tools to guide professional researchers and citizens to build the right project designs [ 11 , 12 ], integrate working evaluations [ 9 ], and consider several factors for successful CS projects [ 2 ]. It also needs to be established how to include diverse groups of participants, including the ones with a low interest in nature and environmental issues.

Secondly, we recommend to involve participants more intensively in agenda setting and research design . Currently, the threshold to participate in CS projects tends to be fairly low, but so is the level of control and participation. Tasks of citizen scientists are typically limited and so is their sense of project ownership, although the likelihood of actual effects taking place increases with an increased degree of control for participants [ 3 ]. For instance, a number of projects report a rise or restoration of trust in local authorities and research institutions ‘due to the co-production process and the appreciation of local knowledge’ [ 3 , 13 ].

There is ample potential to increase participation to more shared decision-making on the purpose and design of the research. An important step would be to open up the drafting of research agendas to diverse groups of citizens and societal actors. This type of citizen involvement is already common practice in other fields of research. One might look at some research fields within health and healthcare studies as good practices. ‘Nothing about us without us’ has become a guiding principle, also within health research (see one of our other studies, on public engagement in psychiatry research [ 14 ]).

In the Netherlands, it is becoming common practice for experts by experience (current patients, recovered patients, patient associations) to have a seat at the table when funding decisions are made. Funding agencies increasingly demand applicants to demonstrate how they included patients or other experts by experience in the development of their research proposal. Funding agencies also include patient associations in the development of their research and funding agendas. These practices show that more shared-decision making processes are possible. We consider three conditions that are crucial for meaningful involvement: A) leadership and management of funding agencies to actively value and endorse public engagement leading to changes in their modus operandi; B) training and support for participating citizens, experts by experience and other societal stakeholders; C) researchers who do not regard public engagement as just another box to tick, but who truly integrate public engagement in their research design. This also means these researchers should be incentivised to integrate public engagement in their research, which points to necessary changes in the way they are recognised and rewarded [ 15 ].

Lastly, we recommend to employ public involvement as an extra stimulus for the practical application of knowledge . For professional scientists, the participation of volunteers in research has concrete value. They use the inputs to improve data availability, improve data quality and for their publications. For participants, the benefit is less tangible. Often, their only reward is the joy of the experience itself. However, as participants contribute more, there is a risk of exploitation. We emphasise that intrinsic motivations are most important for participants, but these motivations go beyond the joy of the experience, such as learning, environmental concern, making a difference, and social aspects of participation [ 2 , 16 ]. Rewards should fit these main drivers of participants for instance by showing how their engagement makes a difference, and by public acknowledgement for their work. A stronger incentive for participation could be provided by showing how the research contributes to the improvement of the (local) natural environment, water quality and biodiversity. Therefore, researchers should provide the volunteers with feedback about the results of the study to which they contributed. Beyond this act of courtesy, they should derive inspiration from the interaction with societal actors to focus more on the societal impact of their work. Some scholars emphasise how several motivations and effects of CS projects reinforce one another to create a desired upwards spiral (e.g. more knowledge and scientific literacy → more environmental concern → intrinsic motivation to make a difference → greater participation in CS projects → more knowledge and scientific literacy) [ 2 ], [ 3 ]. Professional scientists could and should play an active role in realising these societal effects.

In all, citizen science has great potential in water quality research. In fact, numerous projects already illustrate the value of CS to improve water quality around the world. It may help fight the dire threats of water pollution, by raising water awareness, strengthening public support for research, and ultimately for better policies and changes in behaviour. Yet, to reap success with citizen science fully, it should be purposefully designed for such broader societal goals. Therefore, efforts must be made to get a better understanding of the effects of research participation on volunteers, to involve citizen scientist in research agenda setting and the design of research projects, and to listen to them for the practical application of research results.

This article is based on the Dutch report Scholten W, Schölvinck AFM, Van Ewijk S, Diederen PJM. Open science op de oever–Publieke betrokkenheid bij onderzoek naar waterkwaliteit. The Hague: Rathenau Instituut; 2020. Available from: https://www.rathenau.nl/nl/vitale-kennisecosystemen/open-science-op-de-oever [ 17 ].

• 1. OECD. Diffuse Pollution, Degraded Waters: Emerging Policy Solutions. Paris: OECD; 2017.
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• 15. Felt U. “Response-able practices” or “new bureaucracies of virtue”: The challenges of making RRI work in academic environments. In: Asveld L, Van Dam-Mieras R, Swierstra T, Lavrijssen S, Linse K, Van den Hoven J, editors. Responsible Innovation 3: A European Agenda? Cham: Springer; 2017. pp. 49–68.

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Home > Books > Pollution - Annual Volume 2024 [Working Title]

Advances in Sustainable Strategies for Water Pollution Control: A Systematic Review

Submitted: 10 September 2022 Reviewed: 16 September 2022 Published: 10 November 2022

DOI: 10.5772/intechopen.108121

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Pollution - Annual Volume 2024 [Working Title]

Dr. Ismail M.M. Rahman and Dr. Zinnat Ara Begum

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Various technologies, strategies, and policies have been implemented to improve water quality worldwide. This systematic review comprehensively appraises technologies, strategies, and water pollution control policies enacted worldwide between 2000 and 2021. Five databases, Web of Science, PubMed, Scopus, Google Scholar, and Library of Congress, were used for the search. After screening, 89 eligible articles were selected from 2119 documents for further analysis. Selected articles were included: (1) 31 articles covered policies and strategies enacted for controlling water pollution, (2) 47 articles focused on sustainable technologies to control water pollution in different countries, and (3) 11 articles were Nature-based solutions related. Sustainable technologies identified were: aquatic vegetation restoration technology, eco-remediation bio-manipulation technology, wetlands rehabilitation technology, floating aquatic-plant bed systems, and adsorption technology. Most of these methods are geared toward reducing pollutant levels in industrial and agricultural wastewater. Also, most policies are geared toward the manufacturing and farming industries, respectively. Nature-based solutions identified were horizontal-flow treatment wetlands (HFTWs) and constructed wetlands. Furthermore, the current one is atomic layer deposition (ALD).

• sustainable technologies
• water policy
• pollution control strategies

Author Information

Clement kamil abdallah *.

• Department of Environment and Sustainability Science, University for Development Studies, Ghana

Samuel Jerry Cobbina

Khaldoon a. mourad.

• Lund University, Sweden
• The Centre for Sustainable Visions, Sweden

Abu Iddrisu

• Environmental Protection Agency, Ghana

Justice Agyei Ampofo

*Address all correspondence to: [email protected]

1. Introduction

Pollution of water sources includes the introduction of harmful substances into aquatic ecosystems. This indicates that a material or substances have accumulated in the water supply to unhealthy levels, endangering human health, animal, and plant life [ 1 ]. Substances, organic and inorganic, as well as biological, radiological, and thermal, can deteriorate the quality of water to the point where it is no longer usable. In addition, pollution can come from different or single sources, known as a point source and nonpoint source pollution. Point source pollution is an identifiable source of pollution, such as a drain or pipe. An example is the frequent release of industrial wastewater into rivers and the sea. Nonpoint source pollution refers to stormwater runoff that gathers impurities along its path to surface water bodies or aquifers from diffuse sources such as buildings, pavement, and agricultural fields [ 2 ]. As a result of these pollutants, the water is unfit for human, animal, or ecological consumption or use.

Furthermore, available freshwater in the world is gradually reducing due to high pollution levels from human and industrial activities. For example, one of humanity’s critical environmental challenges is the contamination of freshwater resources from increasing industries and natural compounds. In addition, rapid population growth and advancing industrialization have increased the demand for water in many countries and parts of the world, a precious commodity due to the adverse effects of climate change. According to Vörösmarty et al. [ 3 ], over 80% of the world’s population is exposed to water security threats.

An increasing number of emerging contaminates are entering water systems from industrialization and human activity, such as personal care products, pharmaceuticals, heavy metals, detergents, and pesticides. These chemical compounds are released into water bodies causing unprecedented health hazards. More so, water waterborne diseases and microorganisms are found virtually everywhere. These microorganisms enter waterways through septic tanks, farm runoff, storm drains, and meat and other food processing industries.

Countries and institutions worldwide have become increasingly conscious of and concerned about water pollution in recent years. In order to keep water supplies clean in the long run, advanced sustainable pollution control methods have been developed on a global scale [ 4 ]. Water pollution can be prevented, controlled, and reduced by measures including source reduction (or “pollution prevention at the source”), the precautionary principle, and the licensing of wastewater discharges by regulatory institutions [ 5 ].

Establishing policies and strategies and developing cutting-edge technology in water pollution are inherently beneficial since they help regulate and enhance water quality, avoiding unfavorable health effects. Progress in water pollution control dates back to the industrial revolution era [ 6 ]. The Federal Water Pollution Control Act (1948) followed the Chicago Act (1881) as the first significant water pollution regulation in the United States. Since then, several regional, national, and international systems have been implemented to address these issues [ 7 ]. At the continental level, the European Union (EU) Water Directive, adopted in 2000, provided recommendations for safeguarding water on continental scale natural formations such as river basins [ 8 , 9 , 10 , 11 ]. The most prevalent methods used to control local water pollution have been the ban on dumping garbage into rivers and the 3Rs (reduce, reuse, and recycle) approach to trash management [ 1 , 12 ].

In light of these challenges, much attention has been focused on finding ways to control pollution and reclaim wastewater. Moreover, develop effective and cost-efficient methods while protecting the environment and human health. In recent years, extensive research has been conducted to identify realistic and alternative water and wastewater treatment systems. Toxic contaminants in water and wastewater can be removed using various techniques, including coagulation, membrane process, adsorption, dialysis, foam flotation, osmosis, photocatalytic degradation, and biological approaches. However, their widespread implementation has been hampered by issues such as processing efficiency, energy demand, engineering knowledge, economic value, and infrastructure.

As stated by Moher et al. [ 13 ] and Tawfik et al. [ 14 ], posing the review’s objective is imperative in any systematic review study. Therefore, the main objective of this systematic review is to identify various advanced strategies, policies, technologies, and Nature-based solutions enacted in different countries to control water pollution. In addition, the chapter also summarized policy implementation gaps in African and Asia countries, Europe, and North American countries. Finally, the review identified knowledge and research gaps relevant for further investigations.

2.1 Search strategy

The Preferred Reporting Items for Systematic Review and Meta-Analysis (PRISMA) guidelines were used to conduct this thorough systematic review [ 15 ]. The search focused on articles published from 2000 to August 2022. Five scientific databases (Web of Science, Google Scholar, PubMed, Scopus, and Library of Congress) were searched using a systematic screening approach to identify water pollution control strategies and technologies published in peer-reviewed journals. The search terms were water pollution, aquatic pollution, river basin pollution, pollution control policies, management strategies, pollution prevention programs, and cutting-edge pollution mitigation techniques. Following the establishment of inclusion and exclusion criteria, pertinent articles were chosen. Only English-language sources were considered, and it was further supplemented by a search of a reference list of the most relevant articles.

2.2 Eligibility criteria and data extraction

Four procedures were used to find appropriate manuscripts for the review ( Figure 1 ). To begin, we imported all of the manuscripts we could find from our downloads into EndNote X8. This purpose was to weed out any papers that had already been chosen. Also, titles and abstracts were used to determine which remaining publications were relevant. In addition, we read the articles in their entirety to ensure they fulfilled the criteria for this systematic review. All remaining papers were then carefully examined to ensure they fulfilled the inclusion criteria in Table 1 . Water pollution control policies, strategies/technologies, initiation date/period, authors’ names, and publication year are all topics covered by the data extracted from the chosen publications.

The screening process of articles.

Inclusion and exclusion criteria for selection of articles.

3.1 Characteristics of literature

After the duplicates were taken out, 2119 papers were reviewed using only their titles and abstracts ( Figure 1 ). After the above process, 227 articles were found to be relevant to the review’s objectives. However, only 89 papers met the criteria for inclusion. The review included articles published after 2001 focusing on groundwater and surface pollution control strategies and recent advances in suitable nature-based solutions. Moreover, articles on water pollution control using cutting-edge technologies were included ( Table 2 ).

Distribution of included articles.

3.2 Characteristics of the retained studies

The following sections describe the features of the included study. The included articles were made up of cross-sectional and review papers. Within the included papers, articles that focused on sustainable technologies were (n = 47) 52.8%. In total, 34.8% of the articles concentrated on policies and strategies. In total, 12% (n = 11) of the papers were Nature-based solution-related topics ( Table 2 ).

Summary of technology type, pollutant, and sources of pollution.

4. Nature-based solution (NBS) strategies for water pollution control

4.1 constructed wetlands (cws).

Constructed wetland technology has been around for quite some time ( Table 3 ). It has widespread use and is well-established in eastern and western Europe and North America, but it is hardly ever used in Africa and the Middle East [ 4 ]. However, most European countries are beginning to focus on CWs because of their effectiveness in amicrobial and antibiotic removal from wastewater [ 54 ]. Its function is based on natural materials and processes facilitated by interactions between the plant’s main system components, including the plants, substrate media, wastewater, and microorganisms. These components naturally develop within the system [ 4 ]. Because the system is composed mainly of soil, gravel, and plants rather than nonrenewable elements such as concrete or steel, CWs are highly valued domestically [ 55 ]. Using readily available material is crucial for cost-effectiveness and stimulating local and national economies, as most of the components for a CW can be obtained from domestic suppliers [ 56 ]. In addition, hybrid CW is noted to be very efficient in removing phosphorus load from agricultural wastewater [ 54 , 57 ].

4.2 Horizontal-flow treatment wetlands (HFTWs)

The world’s attention has been drawn to NBS for solving most of its environmental challenges. HFTW is one of the recent advances in developing a sustainable solution to control water pollution worldwide [ 58 ]. To facilitate horizontal flow through the filter media, horizontal-flow treatment wetlands (HFTWs) are constructed from gravel beds planted with emergent wetland vegetation [ 59 ]. An anaerobic environment can be maintained at a subsurface flow rate if the medium is completely saturated with water. Straining and filtering keep the solids out, while adsorption and absorption of the solubles considerably [ 60 ]. Chemical and biological processes in the filter medium play a significant role in further transforming and degrading the retained chemicals. The root zone is a dynamic area that facilitates biofilm adhesion, oxygen exchange, and the maintenance of hydraulic flow [ 61 ].

5. Policies for agriculture and industrial pollution control

Voluntary approach (VA) and informal regulations are other approaches to abate water pollution. Furthermore, serving as an alternative policy to market-based and prescriptive. The approach offers polluters incentives through environmental leadership or cost-sharing programs [ 62 ]. Policies identified in this review concerning this approach are as follow: U.S. 33/50 program on toxic releases is voluntary regulation implemented in 1988 to reduce emissions of 17 chemicals to water, soil, and air by 33% by 1992 and 50% by 1995 [ 63 ]. The effectiveness of this policy is mixed, as researchers have different views. Bi and Khanna [ 64 ] revealed that pollution reduction could not be attributed to the 33/50 program. However, other researchers attributed the significant decline in the 33/45 releases to participation in the program [ 65 ]. Compared with the mandatory regulations, it is unclear if the VA positively impacts pollution control and improves water quality [ 66 ]. Another VA approach identified in the review is Mexico’s Clean Industry Program. Industries participate in this voluntary program to improve their knowledge of current pollution control strategies. It was observed that dirty industries punished by the regulatory authority are more likely to participate in the program. Also, the effectiveness of sectors participating in the program to control pollution was not substantially different from the nonparticipants [ 67 ].

5.1 Environmental liability policies

These policies are pretty standard, especially in the developed world. It rules that the cost of ambient water pollution should be internalized. Liabilities are designed to support the “Polluter Pay Principle”; however, polluters do not usually pay for the damages [ 68 ]. Similar to developing and developed countries, it became relevant when the EU adopted the Environmental Liability Directive (ELD) in 2004. The directive holds polluters strictly responsible for the environmental damage they cause to water and requires regulatory authorities to ensure that polluters restore damages to nature in member countries [ 69 ]. Water pollution control in South Africa is regulated by the National Water Act 36 of 1998. This Act’s primary objective is to prevent water resource degradation. Section 19 of the Act stipulates that any person, organization, or owner of land whose activities have caused or are likely to cause water resource pollution should put up measures to stop or prevent it from happening [ 12 ].

6. Discussion

6.1 technologies for water pollution control.

This study attempted to systematically analyze some countries’ existing literature on water pollution control strategies and technologies. Heavy industrialization in agriculture, pharmaceuticals, and food processing has resulted in the pollution of water bodies in the world. A rigorous review sourced from different platforms, including the Web of Science and Scopus, has resulted in 89 articles related to the research on advanced water pollution control strategies. The technologies captured in this review focused more on preventing inorganic pollution than organic pollution. Moreover, most of the pollutants are inorganic pollutants.

Electrodialysis (ED) is remarkable in removing chromium and arsenic from water polluted by sources such as textile dyeing, leather tanning, paints, and pigment industries [ 70 ]. ED technology can reclaim wastewater and recover water through concentration, dilution, desalination, regeneration, and valorization. Gurreri et al. [ 71 ] reported that factory plants had started large-scale installation for industrial wastewater treatment. However, despite the advancement in electrodialysis development, its liquid membrane generates bubbles at the electrodes, making it unstable, and a voltage of 300 V can easily puncture the liquid membrane [ 16 ].

From the systematic review, atomic layer deposition (ALD) is frequently used for aquatic remediation [ 29 ]. Cyanide ions, heavy metals, and other toxic substances can be removed from wastewater effectively by ion exchange [ 72 ]. ALD is considered the most advanced version of traditional chemical vapor deposition. Among the thin film deposition methods for wastewater treatment, ALD has become the most attractive because of its ability to work perfectly on complex three-dimensional surfaces and the uniqueness of its uniform deposition [ 73 , 74 ].

Antibiotic contamination of drinking water has recently reached epidemic proportions. Shukla et al. [ 75 ] reported that sawdust, a relatively inexpensive and abundant material, was investigated as an absorbent for removing heavy metals and other pollutants. Sawdust has been a proven advanced and scalable technology for removing contaminants from water. Sulfonated sawdust (SD-SO 3 H) exhibited high capacity in the removal of antibiotics such as sulfamethoxazole (SMX) and tetracycline (TC) [ 76 ]. Also, treated mahogany sawdust as a biosorbent effectively removed Nickel ions (Ni 2+ ) from industrial wastewater [ 77 ]. Textile industries consume many dyes to colorate fabrics, and the waste from these activities is often discharged into water bodies in countries like China. Research reports by Saroha & Ghosh [ 18 ] have shown that sawdust is very effective in removing safranin-O dye. In the same study, the Arachis hypogaea (peanut hull) shell has been proven very effective in eliminating Sefranin-O dye. This technology is inexpensive because it is made from waste materials from wood products and peanut hulls which can easily be found in our environment. Therefore, low-income countries can adopt it to prevent industrial pollution of water bodies.

Water hyacinth is identified as an invasive weed that threatens the existence of aquatic life. The presence of water hyacinth depletes the oxygen and nutrient levels in the area where they grow. Additionally, it can also obstruct water movement. It is, however, a noxious plant, but one that is also rich in invaluable chemicals such as cellulose, lignin, and hemicellulose, which are found inside. It can be used as a biofuel with the help of these chemicals [ 43 ]. Its biosorption ability to reduce various contaminants in wastewater has been well studied [ 78 ]. It can minimize physiochemical properties such as total dissolved solids (TDS), total suspended solids (TSS), chemical oxygen demand (COD), biological oxygen demand (BOD), and reduce heavy metals and dyestuffs concentrations in industrial wastewater [ 79 ].

Water contaminants can be successfully removed through membrane separation, using little energy and leaving a small carbon footprint. The most critical challenge in developing membrane technology is finding a low-cost, stable, flexible, and multifunctional material [ 41 ]. Graphic carbon nitrite has emerged as a promising membrane material because of its unique structural properties and remarkable catalytic activity. According to Gao et al. [ 80 ], graphic nitrates showed effective and efficient photodegradation and adsorption properties for removing organic pollutants from wastewater.

Persistent pollution from factories has degraded our freshwater supplies and made them unsafe to drink for decades. Since industrialization increased waste creation, this has become extremely problematic to handle. Researchers have suggested that creating tools to cut down on or eliminate industrial waste entirely is the greatest approach to find a long-term solution to this issue [ 23 ]. China, for instance, has spent in creating new cutting-edge technologies for treating industrial wastewater after a number of measures failed to improve river water quality [ 81 , 82 ]. In Belin, for instance, a phosphorus elimination plant was built to treat the effluent of the pharmaceutical industry in order to limit the quantity of phosphorus discharged into the rivers [ 37 ].

7. Policy gaps and implementation challenges in Asia and Africa

The enforcement gap is the major challenge in implementing China’s water pollution control policies and regulations. China is recognized as one of the countries in the developing world with solid institutions and comprehensive environmental regulations [ 83 ]. Nevertheless, the enforcement gap is identified in its political, economic, and social factors that prevent China’s comprehensive environmental policies from resulting in clean rivers. Politically, the central government is strong and can create policies without much stakeholder engagement or discussion. An example of such political power was when the central government directed Jiangsu Province to clean Tai lake by 1998. Though the standards were met by the deadline, in-depth examination revealed that most factories cheated to pass the inspection [ 81 ]. This directive was either issued with little or no engagement from the stakeholders. Also, complex and fragmented institutional arrangements challenged the “333” integrated strategy [ 84 ]. The fragmented authoritarian structure of China’s government is adversely affecting their efforts to keep their water and rivers clean.

Furthermore, Environmental Protection Bureaus (EPBs) are often found under several bureaucracies and answer to many bureaucracies and local governments [ 85 ]. This can make their work very cumbersome and ineffective. To make EPBs effective and efficient, their efforts should be decentralized to all local governments within China. Moreover, Gao et al. [ 86 ] and Han et al. [ 84 ] identified a lack of incentives for government officials or penalties and complex water administration as challenges for implementing water pollution control measures in China. Another issue undermining the ineffectiveness of water pollution control measures is the lack of awareness of the dangers of water pollution [ 81 ]. Despite the increase in awareness, a survey conducted in rural China revealed that lack of environmental consciousness was cited as one of the significant reasons for deteriorating environmental conditions [ 87 ].

India’s water pollution management has undergone significant reforms in the past four decades. However, implementation challenges persist [ 88 ]. Several ministries deal with the Water Prevention and Control of Pollution Act, which delays decision-making, inter-sectoral conflicts, and fragmentation of efforts [ 89 ]. The same gap is identified in Pakistan, where multiple authorities oversee the water sector with various regulations and overlapping responsibilities [ 90 ]. To avoid this, a unified framework can be created for decision-making with representation from each ministry and stakeholder. Also, stakeholder participation is identified as a gap impeding India’s river basin conservation plan [ 91 ]. In Pakistan, industries are made to self-monitor and report their environmental management situation under the PEPA Act [ 92 ]. Alam [ 93 ] said that industries discharge low effluent standards into wetlands and rivers in Pakistan. In Ethiopia, there are discrepancies between the nicely crafted policies and practices. For example, there are no centralized water quality database, effluent standards, and water quality guidelines for industries [ 94 ]. Coupled with this, Addis Ababa, as the capital city, lacks a proper drainage system [ 95 ]. As a result, domestic and industrial wastewater is quickly discharged into river bodies. It has made it almost impossible to control river pollution.

South African Water Act is viewed as s the Rolls Royce of IWRM legislation [ 96 ]. However, its implementation became a difficult task. The critical challenge to the performance of the Water Act was that it was too overambitious to implement vast functions simultaneously [ 97 ]. Though the Act was written so it could be implemented in phases, the implementing authority was overwhelmed with multiple tasks simultaneously with limited resources [ 96 ].

8. Policy gaps and implementation challenges in Europe and North America

In the developed world, water pollution control policies have recorded success in keeping rivers and watersheds clean [ 98 , 99 , 100 ]. This success is attributed to the vital institutions, available funding, and human resources [ 62 ]. Despite the success stories of these policies, there are several accounts of policy gaps and challenges hampering the attainment of pollution-free rivers [ 101 ]. Regarding water quality trading in the USA, Canada, and Australia, researchers have recounted instances where buyers were not available to purchase pollution credit from sellers [ 99 ]. Many in the USA have no trading [ 102 ]. Claire and Bryan [ 103 ] described it as another “polluter-pays scheme” by more giant industries. More prominent industries buy salinity credit allocation from smaller enterprises if they exceed their limits in Australia Hunter River. This can make more giant industries relax on exploring more innovative technologies to prevent pollution and rely on credits from smaller enterprises. Farmers in Canada had reservations about phosphorous trading in the South Nation River watershed. They feared that blame would come if phosphorus standards were not met [ 104 ]. Because water quality trading permits polluters to buy credits instead of reaching their pollution targets, such programs could result in harmful pollution hotspots if one facility purchases too many credits. Individual markets can implement hot spot prevention techniques but are not obligated to do so [ 101 ].

The European Union report on the Water Framework Directive (WFD) recommended that Germany and other EU countries improve their water management. This signals gaps in their policies and implementation process. European Commission assesses that measures to protect freshwater are not ambitious, demonstrating very low clean water aspirations. Under this same circumstance, other countries are still opting for the easy way out and pushing for the Water Framework Directive to be significantly weakened. This was noticed during the commission’s fitness check of the WFD [ 105 ].

9. Knowledge gap and future research

This systematic review focuses on the last 21 years. The results show that research on water pollution control strategies and technology in developing and developed countries focused on industrial and agricultural pollution control (point source pollution) instead of urban water pollution control. Therefore, it is suggested that future review efforts include the following. First, researchers can do a systematic review of urban water pollution control strategies and technologies with a more extended review period of 30 years. Strategies and technologies to control urban water pollution should focus on sanitary sewage, runoff, separated sewage system, storm drainage, and combined sewage system. A longer review period will give new insights and a good picture of urban water pollution control. Second, considering the gaps and policy implementation challenges, subsequent researchers can do a systematic review and meta-analysis on the impact of water pollution control policies and strategies in developing and developed countries.

10. Conclusion

A systematic review was conducted to identify advanced water pollution control strategies, technologies, and policies for published articles from 2001 to 2022. The papers used in this analysis fell into one of three groups: (1) that introduce policies and strategies to control water pollution worldwide, (2) articles that introduce different sustainable technologies to control water pollution in different countries, and (3) Nature-based solutions related strategies to control water pollution. Category two of the review was further classified into technology type, pollutant, and source of pollution. Furthermore, category one was also further disintegrated into different policy types. As a result, water pollution control policies identified were voluntary approaches and environmental liability policies. Therefore, the main conclusions regarding advanced water pollution control strategies, policies, and technologies in the countries included in the review can be drawn as follows:

Among the technologies identified, absorption is common in advanced methods for controlling pollutants such as cyanobacteria, nutrients, arsenic, and heavy metals. The primary sources of the contaminants were industries and agricultural farmlands.

Global adoption of green technology should be encouraged to ensure that the water pollution control approach is environmentally friendly, economically feasible, and energy efficient. With these methods, pollutant and nutrient removal will be very efficient. At the same time, carbon footprints will be minimized, and waste will be reduced, and safeguard human health and the environment.

Over ambitious policies and strategies should be redesigned to promote cooperation between stakeholders and all water users to ensure sustainable water management.

Waste materials such as peanut hulls and sawdust should be considered for water pollution management in future technological developments. This will encourage the recycling of environmental waste while also preventing water contamination at the same time.

Conflict of interest

The authors declare no conflict(s) of interest.

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Water Pollution

Recent publications and news, sociodemographic factors are associated with the abundance of pfas sources and detection in u.s. community water systems, freshwater fish found to have high levels of ‘forever chemicals’, nitrifying microorganisms linked to biotransformation of perfluoroalkyl sulfonamido precursors from legacy aqueous film-forming foams, soil and water pollution and human health: what should cardiologists worry about, the utility of machine learning models for predicting chemical contaminants in drinking water: promise, challenges, and opportunities., more harvard resources.

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Discharge from a Chinese fertilizer factory winds its way toward the Yellow River. Like many of the world's rivers, pollution remains an ongoing problem.

Water pollution is a rising global crisis. Here’s what you need to know.

The world's freshwater sources receive contaminants from a wide range of sectors, threatening human and wildlife health.

From big pieces of garbage to invisible chemicals, a wide range of pollutants ends up in our planet's lakes, rivers, streams, groundwater, and eventually the oceans. Water pollution—along with drought, inefficiency, and an exploding population—has contributed to a freshwater crisis , threatening the sources we rely on for drinking water and other critical needs.

Research has revealed that one pollutant in particular is more common in our tap water than anyone had previously thought: PFAS, short for poly and perfluoroalkyl substances. PFAS is used to make everyday items resistant to moisture, heat, and stains; some of these chemicals have such long half-lives that they are known as "the forever chemical."

Safeguarding water supplies is important because even though nearly 70 percent of the world is covered by water, only 2.5 percent of it is fresh. And just one percent of freshwater is easily accessible, with much of it trapped in remote glaciers and snowfields.

Water pollution causes

Water pollution can come from a variety of sources. Pollution can enter water directly, through both legal and illegal discharges from factories, for example, or imperfect water treatment plants. Spills and leaks from oil pipelines or hydraulic fracturing (fracking) operations can degrade water supplies. Wind, storms, and littering—especially of plastic waste —can also send debris into waterways.

Thanks largely to decades of regulation and legal action against big polluters, the main cause of U.S. water quality problems is now " nonpoint source pollution ," when pollutants are carried across or through the ground by rain or melted snow. Such runoff can contain fertilizers, pesticides, and herbicides from farms and homes; oil and toxic chemicals from roads and industry; sediment; bacteria from livestock; pet waste; and other pollutants .

Finally, drinking water pollution can happen via the pipes themselves if the water is not properly treated, as happened in the case of lead contamination in Flint, Michigan , and other towns. Another drinking water contaminant, arsenic , can come from naturally occurring deposits but also from industrial waste.

Freshwater pollution effects

Water pollution can result in human health problems, poisoned wildlife, and long-term ecosystem damage. When agricultural and industrial runoff floods waterways with excess nutrients such as nitrogen and phosphorus, these nutrients often fuel algae blooms that then create dead zones , or low-oxygen areas where fish and other aquatic life can no longer thrive.

Algae blooms can create health and economic effects for humans, causing rashes and other ailments, while eroding tourism revenue for popular lake destinations thanks to their unpleasant looks and odors. High levels of nitrates in water from nutrient pollution can also be particularly harmful to infants , interfering with their ability to deliver oxygen to tissues and potentially causing " blue baby syndrome ." The United Nations Food and Agriculture Organization estimates that 38 percent of the European Union's water bodies are under pressure from agricultural pollution.

Globally, unsanitary water supplies also exact a health toll in the form of disease. At least 2 billion people drink water from sources contaminated by feces, according to the World Health Organization , and that water may transmit dangerous diseases such as cholera and typhoid.

Freshwater pollution solutions

In many countries, regulations have restricted industry and agricultural operations from pouring pollutants into lakes, streams, and rivers, while treatment plants make our drinking water safe to consume. Researchers are working on a variety of other ways to prevent and clean up pollution. National Geographic grantee Africa Flores , for example, has created an artificial intelligence algorithm to better predict when algae blooms will happen. A number of scientists are looking at ways to reduce and cleanup plastic pollution .

There have been setbacks, however. Regulation of pollutants is subject to changing political winds, as has been the case in the United States with the loosening of environmental protections that prevented landowners from polluting the country’s waterways.

Anyone can help protect watersheds by disposing of motor oil, paints, and other toxic products properly , keeping them off pavement and out of the drain. Be careful about what you flush or pour down the sink, as it may find its way into the water. The U.S. Environmental Protection Agency recommends using phosphate-free detergents and washing your car at a commercial car wash, which is required to properly dispose of wastewater. Green roofs and rain gardens can be another way for people in built environments to help restore some of the natural filtering that forests and plants usually provide.

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Water pollution Its causes and effects

Suaad Hadi Hassan Al-Taai 1

Published under licence by IOP Publishing Ltd IOP Conference Series: Earth and Environmental Science , Volume 790 , First International Virtual Conference on Environment & Natural Resources 24-25 March 2021, College of Science, University of Al-Qadisiyah, Iraq Citation Suaad Hadi Hassan Al-Taai 2021 IOP Conf. Ser.: Earth Environ. Sci. 790 012026 DOI 10.1088/1755-1315/790/1/012026

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The topic of water contamination is one of the significant studies that, because of its great effect on the lives of humans, animals and plants alike, has attracted the attention of researchers and those interested in the environment. It is not less harmful than contamination of the air and soil, but more closely linked to them. The research centered on the study of the notion of pollution in general, then the notion of water pollution and its sources. In addition to groundwater contamination, there have been many pollution processes, the most important of which are biological, physical, and by dumping solid and liquid waste into waters of rivers, lakes and seas.

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EPA's research is advancing integrated water quality and watershed management tools for protecting and restoring water resources, their associated ecosystems, and the human uses they support. 

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Wastewater Pollution

Turning a Critical Problem into Opportunity

Wastewater is a major threat to nature and human health.

Without adequate treatment, wastewater can contribute to habitat loss and extinction. TNC is actively addressing this through innovative science, strategic communications and policy interventions.

A Scary Status Quo

Every day 80% of the world’s wastewater enters our environment completely untreated, jeopardizing nature and public health, with far-reaching consequences for climate resilience, aquatic biodiversity and food and water security and access. Wastewater introduces a toxic cocktail of contaminants that threaten our food and water security as well as marine species. 

What's in wastewater? Pathogens, pharmaceuticals, microplastics, heavy metals, endocrine disruptors and more.

Our existing wastewater treatment systems allow us to “flush it and forget it,” avoiding the complex reality of wastewater pollution. Ignoring this critical issue leads to dangerous consequences, some of which we are already seeing like closed beaches, collapsed fisheries and algal blooms that suffocate aquatic life. 

Wastewater Pollution is Everywhere

TNC’s Solution

TNC scientists and conservation practitioners are addressing the dangerous impacts of wastewater pollution with a whole-system approach.

In addition to TNC’s on-the-ground projects across the globe, our dedicated wastewater pollution program is working across the Pacific to coordinate partners, develop foundational science and find solutions that work.

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Eyes on wastewater.

Wastewater can often be a hidden threat. Click through this slideshow to see what's just below the surface.

Ocean Sewage: 2 divers inspect the effects of Delray Beach sewage outfall on the coral reef in Florida. © Steve Spring/Palm Beach County Reef Rescue

Coastal Pollution: Riverine discharges to coastal areas. Studies have linked wastewater pollution to seagrass die-offs, harmful algal blooms and weakened reefs. © Malik Naumann/Flickr

Sewage Contaminated Water: Ignoring wastewater pollution can have dangerous consequences, some of which we are already seeing like closed beaches, collapsed fisheries and algal blooms. © Brian Auer

Wastewater Pollution: Wastewater introduces a toxic cocktail of contaminants that threaten our food and water security as well as marine species. © Tom Fisk

Marin County Sewage: Richardson Bay in Marin County, CA is one of the sites in the Bat Area that has experienced sewage spills. © KQED Quest/Flickr

Strategic Communications & Policy

For too many, wastewater pollution flies under the radar or is simply categorized as someone else’s problem. Cultural taboo, combined with misconceptions about the capacity of oceans and other water systems to absorb wastewater, limits our ability to find and implement solutions. So much of the answer hinges on raising awareness.

It's time the world understood the critical threat wastewater pollution poses to humans and the natural systems we depend on.

That’s why TNC is building awareness and education through partnerships to reach broader audiences and drive campaigns that reduce stigma around wastewater and inspire action. We’re working across sectors to produce and share research, tools, and best practices while highlighting the intersections between wastewater pollution, public health and the environment. 

COLLABORATION IN ACTION

• TNC’s collaboration with the Reef Resilience Network provides wastewater pollution training, tools, and learning resources for coral reef practitioners. 
• Our work alongside partners at the Ocean Sewage Alliance  to build a first-of-its-kind knowledge hub and resource library on marine wastewater pollution. 

POLICY REFORM

If the world is to meet the UN's Sustainable Development Goals , we'll need significant policy reform. Many of the world’s wastewater policies and regulations are inadequate and based on outdated science that neither accounts for modern-day stressors nor recognizes the economic opportunity of wastewater resource recovery. TNC is exploring avenues for policy interventions to reduce and mitigate wastewater pollution for human health and environmental protection.

Coastal Long Island, NY

Nitrogen pollution has had a devastating effect on Long Island’s water quality for decades, causing harmful algal blooms and threatening bivalves, like oysters and mussels, as well as seagrass and salt marsh habitats. TNC’s Long Island team, in collaboration with a myriad of government and private sector partners, knew their restoration work wouldn't be successful without dealing directly with the pollution's source: the island’s half-million septic systems and cesspools. Find out how they worked with policymakers and partners at the federal and local level to secure funding and policy reforms necessary to do just that — from homeowner assistance for upgrading septic systems to building clean water infrastructure across the state that mitigates the effects of wastewater pollution. As of 2024, this coalition continues to work on a major ballot valued at $6B over the next 35 years, to create a county wide water quality restoration act to substantially increase the local funding for clean septic change outs and strategic sewer expansion. This fund would be the key to unlocking federal and state infrastructure funding.

Research & Monitoring

The global scientific community is increasingly recognizing the profound impact that wastewater pollution has on aquatic ecosystems. TNC scientists and field staff are on the front lines monitoring water quality to inform wastewater pollution mitigation and management strategies. 

Studies have linked wastewater pollution to seagrass die-offs, harmful algal bloom events and weakened reefs that can destabilize entire ecosystems. Even coastal wetlands, which naturally absorb nutrients, can become oversaturated when exposed to wastewater pollution over time, making these systems more vulnerable to extreme weather events exacerbated by climate change. 

"Contaminants of emerging concern” (CECs) in wastewater, like  PFAS , pharmaceuticals, and other novel chemicals not only threaten drinking water and human health but are also contaminating coastal waters and fisheries. 

A GLOBAL GOAL FOR OUR OCEANS

TNC’s plan for ocean recovery is expansive. We have a goal of conserving 10 billion acres of ocean worldwide. In order to achieve this goal, we must ensure that wastewater does not threaten the health and quality of the marine waters we protect.

Nature-based Solutions

Nature-based solutions are interventions that harness the power of Earth’s natural features and functions. These can look like dunes and wetlands that insulate coasts from storm surge, or native forest restoration in the face of megafires.

TNC and partners are employing nature-based solutions to address wastewater. One of the most promising solutions our team is studying is constructed wetlands . These are engineered systems designed for wastewater treatment that use natural biological technologies that incorporate wetland vegetation, soils, and microorganisms to remove contaminants.

This can be a cost-effective and sustainable option, and TNC is implementing solutions like these across the globe. From the Dominican Republic to India, our team is demonstrating that constructed wetlands can be an effective, nature-based mitigation strategy to improve water quality and restore wildlife habitat. 

Constructed Wetlands in Lake Sembakkam

In Chennai, the largest city in India’s southern state of Tamil Nadu, a 100-acre wetland has been restored to protect Lake Sembakkam. Rapid urbanization, including increases in wastewater and stormwater pollution, has caused the lake to degrade over time. This is one of many critical natural wetlands that serve as a lifeline for the city’s people and wildlife—including several rare and threatened species of migratory birds. TNC’s India program helped design and restore these wetlands to support biodiversity and to improve habitat, water quality, groundwater storage and recharge, and recreation landscape. Read more about how these constructed wetlands work and why TNC is expanding the project to the broader system of Chennai’s marshland.

Climate change and wastewater pollution are two inextricably linked crises. 

It’s estimated that wastewater treatment plants account for at least 3% of all greenhouse gas emissions, in addition to supplemental emissions from direct discharge into waterways. Beyond the treatment process, wastewater pollution is also a significant threat to some of the key ecosystems we rely on to store carbon, including mangrove forests and seagrass beds. To complicate the matter, the effects of climate change—from sea level rise to the increase in extreme weather events—are overburdening wastewater treatment systems that are already stressed and outdated. 

But if we change the status quo, addressing wastewater pollution can provide multiple avenues for tackling climate change. It starts with implementing treatment options that better protect carbon-storing ecosystems. These options are even more effective when coupled with investment in innovative practices that divert waste into valuable resources, such as reclaimed water, biofuel and fertilizer.

In Florida, TNC and partners have helped pave the way for more widespread reuse of wastewater, helping craft legislation that bans the use of ocean outfalls that discharge treated wastewater directly to the coastal zone within Southeast Florida by 2025, instead encouraging reuse. 

Make Transformative Change Possible.

We depend on nature, and nature depends on those of us who care enough to stand up for it.

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What is water pollution?

What are the causes of water pollution, categories of water pollution, what are the effects of water pollution, what can you do to prevent water pollution.

Water pollution occurs when harmful substances—often chemicals or microorganisms—contaminate a stream, river, lake, ocean, aquifer, or other body of water, degrading water quality and rendering it toxic to humans or the environment.

This widespread problem of water pollution is jeopardizing our health. Unsafe water kills more people each year than war and all other forms of violence combined. Meanwhile, our drinkable water sources are finite: Less than 1 percent of the earth’s freshwater is actually accessible to us. Without action, the challenges will only increase by 2050, when global demand for freshwater is expected to be one-third greater than it is now.

Water is uniquely vulnerable to pollution. Known as a “universal solvent,” water is able to dissolve more substances than any other liquid on earth. It’s the reason we have Kool-Aid and brilliant blue waterfalls. It’s also why water is so easily polluted. Toxic substances from farms, towns, and factories readily dissolve into and mix with it, causing water pollution.

Here are some of the major sources of water pollution worldwide:

Agricultural

Toxic green algae in Copco Reservoir, northern California

Aurora Photos/Alamy

Not only is the agricultural sector the biggest consumer of global freshwater resources, with farming and livestock production using about 70 percent of the earth’s surface water supplies , but it’s also a serious water polluter. Around the world, agriculture is the leading cause of water degradation. In the United States, agricultural pollution is the top source of contamination in rivers and streams, the second-biggest source in wetlands, and the third main source in lakes. It’s also a major contributor of contamination to estuaries and groundwater. Every time it rains, fertilizers, pesticides, and animal waste from farms and livestock operations wash nutrients and pathogens—such bacteria and viruses—into our waterways. Nutrient pollution , caused by excess nitrogen and phosphorus in water or air, is the number-one threat to water quality worldwide and can cause algal blooms , a toxic soup of blue-green algae that can be harmful to people and wildlife.

Sewage and wastewater

Used water is wastewater. It comes from our sinks, showers, and toilets (think sewage) and from commercial, industrial, and agricultural activities (think metals, solvents, and toxic sludge). The term also includes stormwater runoff , which occurs when rainfall carries road salts, oil, grease, chemicals, and debris from impermeable surfaces into our waterways

More than 80 percent of the world’s wastewater flows back into the environment without being treated or reused, according to the United Nations; in some least-developed countries, the figure tops 95 percent. In the United States, wastewater treatment facilities process about 34 billion gallons of wastewater per day . These facilities reduce the amount of pollutants such as pathogens, phosphorus, and nitrogen in sewage, as well as heavy metals and toxic chemicals in industrial waste, before discharging the treated waters back into waterways. That’s when all goes well. But according to EPA estimates, our nation’s aging and easily overwhelmed sewage treatment systems also release more than 850 billion gallons of untreated wastewater each year.

Oil pollution

Big spills may dominate headlines, but consumers account for the vast majority of oil pollution in our seas, including oil and gasoline that drips from millions of cars and trucks every day. Moreover, nearly half of the estimated 1 million tons of oil that makes its way into marine environments each year comes not from tanker spills but from land-based sources such as factories, farms, and cities. At sea, tanker spills account for about 10 percent of the oil in waters around the world, while regular operations of the shipping industry—through both legal and illegal discharges—contribute about one-third. Oil is also naturally released from under the ocean floor through fractures known as seeps.

Radioactive substances

Radioactive waste is any pollution that emits radiation beyond what is naturally released by the environment. It’s generated by uranium mining, nuclear power plants, and the production and testing of military weapons, as well as by universities and hospitals that use radioactive materials for research and medicine. Radioactive waste can persist in the environment for thousands of years, making disposal a major challenge. Consider the decommissioned Hanford nuclear weapons production site in Washington, where the cleanup of 56 million gallons of radioactive waste is expected to cost more than $100 billion and last through 2060. Accidentally released or improperly disposed of contaminants threaten groundwater, surface water, and marine resources.

To address pollution and protect water we need to understand where the pollution is coming from (point source or nonpoint source) and the type of water body its impacting (groundwater, surface water, or ocean water).

Where is the pollution coming from?

Point source pollution.

When contamination originates from a single source, it’s called point source pollution. Examples include wastewater (also called effluent) discharged legally or illegally by a manufacturer, oil refinery, or wastewater treatment facility, as well as contamination from leaking septic systems, chemical and oil spills, and illegal dumping. The EPA regulates point source pollution by establishing limits on what can be discharged by a facility directly into a body of water. While point source pollution originates from a specific place, it can affect miles of waterways and ocean.

Nonpoint source

Nonpoint source pollution is contamination derived from diffuse sources. These may include agricultural or stormwater runoff or debris blown into waterways from land. Nonpoint source pollution is the leading cause of water pollution in U.S. waters, but it’s difficult to regulate, since there’s no single, identifiable culprit.

Transboundary

It goes without saying that water pollution can’t be contained by a line on a map. Transboundary pollution is the result of contaminated water from one country spilling into the waters of another. Contamination can result from a disaster—like an oil spill—or the slow, downriver creep of industrial, agricultural, or municipal discharge.

What type of water is being impacted?

Groundwater pollution.

When rain falls and seeps deep into the earth, filling the cracks, crevices, and porous spaces of an aquifer (basically an underground storehouse of water), it becomes groundwater—one of our least visible but most important natural resources. Nearly 40 percent of Americans rely on groundwater, pumped to the earth’s surface, for drinking water. For some folks in rural areas, it’s their only freshwater source. Groundwater gets polluted when contaminants—from pesticides and fertilizers to waste leached from landfills and septic systems—make their way into an aquifer, rendering it unsafe for human use. Ridding groundwater of contaminants can be difficult to impossible, as well as costly. Once polluted, an aquifer may be unusable for decades, or even thousands of years. Groundwater can also spread contamination far from the original polluting source as it seeps into streams, lakes, and oceans.

Surface water pollution

Covering about 70 percent of the earth, surface water is what fills our oceans, lakes, rivers, and all those other blue bits on the world map. Surface water from freshwater sources (that is, from sources other than the ocean) accounts for more than 60 percent of the water delivered to American homes. But a significant pool of that water is in peril. According to the most recent surveys on national water quality from the U.S. Environmental Protection Agency, nearly half of our rivers and streams and more than one-third of our lakes are polluted and unfit for swimming, fishing, and drinking. Nutrient pollution, which includes nitrates and phosphates, is the leading type of contamination in these freshwater sources. While plants and animals need these nutrients to grow, they have become a major pollutant due to farm waste and fertilizer runoff. Municipal and industrial waste discharges contribute their fair share of toxins as well. There’s also all the random junk that industry and individuals dump directly into waterways.

Ocean water pollution

Eighty percent of ocean pollution (also called marine pollution) originates on land—whether along the coast or far inland. Contaminants such as chemicals, nutrients, and heavy metals are carried from farms, factories, and cities by streams and rivers into our bays and estuaries; from there they travel out to sea. Meanwhile, marine debris— particularly plastic —is blown in by the wind or washed in via storm drains and sewers. Our seas are also sometimes spoiled by oil spills and leaks—big and small—and are consistently soaking up carbon pollution from the air. The ocean absorbs as much as a quarter of man-made carbon emissions .

On human health

To put it bluntly: Water pollution kills. In fact, it caused 1.8 million deaths in 2015, according to a study published in The Lancet . Contaminated water can also make you ill. Every year, unsafe water sickens about 1 billion people. And low-income communities are disproportionately at risk because their homes are often closest to the most polluting industries.

Waterborne pathogens, in the form of disease-causing bacteria and viruses from human and animal waste, are a major cause of illness from contaminated drinking water . Diseases spread by unsafe water include cholera, giardia, and typhoid. Even in wealthy nations, accidental or illegal releases from sewage treatment facilities, as well as runoff from farms and urban areas, contribute harmful pathogens to waterways. Thousands of people across the United States are sickened every year by Legionnaires’ disease (a severe form of pneumonia contracted from water sources like cooling towers and piped water), with cases cropping up from California’s Disneyland to Manhattan’s Upper East Side.

A woman using bottled water to wash her three-week-old son at their home in Flint, Michigan

Todd McInturf/The Detroit News/AP

Meanwhile, the plight of residents in Flint, Michigan —where cost-cutting measures and aging water infrastructure created a lead contamination crisis—offers a stark look at how dangerous chemical and other industrial pollutants in our water can be. The problem goes far beyond Flint and involves much more than lead, as a wide range of chemical pollutants—from heavy metals such as arsenic and mercury to pesticides and nitrate fertilizers —are getting into our water supplies. Once they’re ingested, these toxins can cause a host of health issues, from cancer to hormone disruption to altered brain function. Children and pregnant women are particularly at risk.

Even swimming can pose a risk. Every year, 3.5 million Americans contract health issues such as skin rashes, pinkeye, respiratory infections, and hepatitis from sewage-laden coastal waters, according to EPA estimates.

On the environment

In order to thrive, healthy ecosystems rely on a complex web of animals, plants, bacteria, and fungi—all of which interact, directly or indirectly, with each other. Harm to any of these organisms can create a chain effect, imperiling entire aquatic environments.

When water pollution causes an algal bloom in a lake or marine environment, the proliferation of newly introduced nutrients stimulates plant and algae growth, which in turn reduces oxygen levels in the water. This dearth of oxygen, known as eutrophication , suffocates plants and animals and can create “dead zones,” where waters are essentially devoid of life. In certain cases, these harmful algal blooms can also produce neurotoxins that affect wildlife, from whales to sea turtles.

Chemicals and heavy metals from industrial and municipal wastewater contaminate waterways as well. These contaminants are toxic to aquatic life—most often reducing an organism’s life span and ability to reproduce—and make their way up the food chain as predator eats prey. That’s how tuna and other big fish accumulate high quantities of toxins, such as mercury.

Marine ecosystems are also threatened by marine debris , which can strangle, suffocate, and starve animals. Much of this solid debris, such as plastic bags and soda cans, gets swept into sewers and storm drains and eventually out to sea, turning our oceans into trash soup and sometimes consolidating to form floating garbage patches. Discarded fishing gear and other types of debris are responsible for harming more than 200 different species of marine life.

Meanwhile, ocean acidification is making it tougher for shellfish and coral to survive. Though they absorb about a quarter of the carbon pollution created each year by burning fossil fuels, oceans are becoming more acidic. This process makes it harder for shellfish and other species to build shells and may impact the nervous systems of sharks, clownfish, and other marine life.

With your actions

We’re all accountable to some degree for today’s water pollution problem. Fortunately, there are some simple ways you can prevent water contamination or at least limit your contribution to it:

• Learn about the unique qualities of water where you live . Where does your water come from? Is the wastewater from your home treated? Where does stormwater flow to? Is your area in a drought? Start building a picture of the situation so you can discover where your actions will have the most impact—and see if your neighbors would be interested in joining in!
• Reduce your plastic consumption and reuse or recycle plastic when you can.
• Properly dispose of chemical cleaners, oils, and nonbiodegradable items to keep them from going down the drain.
• Maintain your car so it doesn’t leak oil, antifreeze, or coolant.
• If you have a yard, consider landscaping that reduces runoff and avoid applying pesticides and herbicides .
• Don’t flush your old medications! Dispose of them in the trash to prevent them from entering local waterways.
• Be mindful of anything you pour into storm sewers, since that waste often won’t be treated before being released into local waterways. If you notice a storm sewer blocked by litter, clean it up to keep that trash out of the water. (You’ll also help prevent troublesome street floods in a heavy storm.)
• If you have a pup, be sure to pick up its poop .

With your voice

One of the most effective ways to stand up for our waters is to speak out in support of the Clean Water Act, which has helped hold polluters accountable for five decades—despite attempts by destructive industries to gut its authority. But we also need regulations that keep pace with modern-day challenges, including microplastics, PFAS , pharmaceuticals, and other contaminants our wastewater treatment plants weren’t built to handle, not to mention polluted water that’s dumped untreated.

Tell the federal government, the U.S. Army Corps of Engineers, and your local elected officials that you support water protections and investments in infrastructure, like wastewater treatment, lead-pipe removal programs, and stormwater-abating green infrastructure. Also, learn how you and those around you can get involved in the policymaking process . Our public waterways serve every one of us. We should all have a say in how they’re protected.

This story was originally published on May 14, 2018, and has been updated with new information and links.

This NRDC.org story is available for online republication by news media outlets or nonprofits under these conditions: The writer(s) must be credited with a byline; you must note prominently that the story was originally published by NRDC.org and link to the original; the story cannot be edited (beyond simple things such as grammar); you can’t resell the story in any form or grant republishing rights to other outlets; you can’t republish our material wholesale or automatically—you need to select stories individually; you can’t republish the photos or graphics on our site without specific permission; you should drop us a note to let us know when you’ve used one of our stories.

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Mapping the scientific research on non-point source pollution: a bibliometric analysis

• Review Article
• Published: 08 December 2016
• Volume 24 , pages 4352–4366, ( 2017 )

Cite this article

• Beibei Yang 1 ,
• Kai Huang 1 ,
• Dezhi Sun 1 &
• Yue Zhang 1  

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A bibliometric analysis was conducted to examine the progress and future research trends of non-point source (NPS) pollution during the years 1991–2015 based on the Science Citation Index Expanded (SCI-Expanded) of Web of Science (WoS). The publications referencing NPS pollution were analyzed including the following aspects: document type, publication language, publication output and characteristics, subject category, source journal, distribution of country and institution, author keywords, etc. The results indicate that the study of NPS pollution demonstrated a sharply increasing trend since 1991. Article and English were the most commonly used document type and language. Environmental sciences and ecology, water resources, and engineering were the top three subject categories. Water science and technology ranked first in distribution of journal, followed by Science of the total environment and Environmental Monitoring and Assessment . The USA took a leading position in both quantity and quality, playing an important role in the research field of NPS pollution, followed by the UK and China. The most productive institution was the Chinese Academy of Sciences (Chinese Acad Sci), followed by Beijing Normal University and US Department of Agriculture’s Agricultural Research Service (USDA ARS). The analysis of author keywords indicates that the major hotspots of NPS pollution from 1991 to 2015 contained “water,” “model,” “agriculture,” “nitrogen,” “phosphorus,” etc. The results provide a comprehensive understanding of NPS pollution research and help readers to establish the future research directions.

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Acknowledgements

This research was supported by the Fundamental Research Funds for the Central Universities of China (No. 2015ZCQ-HJ-01) and National Natural Science Foundation of China (41301636).

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Yang, B., Huang, K., Sun, D. et al. Mapping the scientific research on non-point source pollution: a bibliometric analysis. Environ Sci Pollut Res 24 , 4352–4366 (2017). https://doi.org/10.1007/s11356-016-8130-y

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• 13 EarthWatch Europe, Oxford, United Kingdom
• 14 National Water Resource Management Agency, Freetown, Sierra Leone

Citizen science (CS) has so far failed to achieve its potential to contribute to water resource management globally despite a significant body of work proclaiming the benefits of such an approach. Also, this work has addressed concerns over precision, accuracy and reliability of methods used. This article presents the findings of a hackathon-type workshop challenge that brought together water quality experts and CS practitioners to explore barriers and possible solutions to mainstream citizen scientist-generated data into national, regional, and global reporting processes, and thereby provide a tangible connection between policy makers and community-based citizen scientists. We present the findings here as a perspective-type summary. This workshop challenge highlighted the breadth and scope of CS activities globally yet recognized that their potential for positive impact is going unrealized. The challenge team proposed that impact could be improved by: developing awareness; applying a simultaneous bottom-up/top-down approach to increase success rates; that local leaders or ‘catalysts' are key to initiate and sustain activities; that generated data need to fulfill a purpose and create required information, and ultimately, lead to actions (data > information > action); recognizing that we are all potential citizen scientists is important; recognizing that “good water quality” is subjective; and lastly that developing a communication gateway that allows bi-directional data and information transfer is essential.

1 Introduction

Water quality monitoring and assessment is an essential prerequisite for sound and robust water resource management. Monitoring objectives, which dictate the monitoring program design can vary, but to understand how the triple planetary crisis of climate change, biodiversity loss and pollution is impacting our freshwaters, the ecosystems they support, and the essential ecosystem services upon which we rely—monitoring programs that deliver long-term, and spatially diverse trend information are required.

The capacity of national authorities tasked with gathering this information varies greatly at the global scale. Many national authorities, especially those in low-income countries, lack the capacity to collect water quality data at the requisite spatial and temporal scales to provide science-based information for water resource management decisions. This deficit of water quality information has been made clear through countries' reporting on SDG indicator 6.3.2 on ambient water quality. In 2021, it was reported that just 1.7 per cent (1,300) of the total water bodies reported on (77,000) were from the lowest income quartile group of UN Member States ( UNEP, 2021 ). At its most basic, reporting on this SDG indicator requires in situ water quality data to be collected on basic physico-chemical parameters from designated monitoring locations on a defined sample collection schedule. A much greater long-term monitoring and assessment capacity is required if countries are to fully understand the pressures and stresses placed upon their water resources than is prescribed by this SDG indicator, but this basic methodology serves as a useful first step and benchmark for countries that are developing and advancing this capacity.

The potential of CS as an effective means to contribute to SDG monitoring is widely recognized ( Fritz et al., 2019 ; Fraisl et al., 2020 ; Ballerini and Bergh, 2021 ). In addition to data provision for water governance, CS also provides opportunities around engagement, education, awareness raising, and action in favor of water quality. CS as a means to fill the water quality data gap has been presented as an alternative data stream for national and global reporting ( Bishop et al., 2020 ; Hegarty et al., 2021 ). As of yet, this potential has not been realized and CS-generated data have so far not contributed to national monitoring systems, nor to water-related regional or global reporting frameworks such as the SDG 6.

Citizen scientists employ various approaches and methods to monitoring ( Blanco-Ramírez et al., 2023 ), and although concerns over accuracy, precision and reliability of citizen-generated data have been considered in several studies ( Quinlivan et al., 2019 ; Moshi et al., 2022 ; Stankiewicz et al., 2023 ), still, there remain barriers to the use of these data. Much work has been done by scientists who have used CS as a strategy for data collection or focused on data accuracy comparisons, by non-governmental organizations or by other local or community groups which have not necessarily impacted the national and political scale for water quality reports. However, their work mostly informs scientist or citizen scientists needs, and much less to enable water governance, civil servants and policy makers to make use and benefit from CS data and its potential.

This article explores the various barriers to incorporate citizen-generated data into national reporting systems and proposes potential solutions to overcome these barriers and thereby empowering the citizen scientists to improve the water quality of their water resources.

2 Innovation workshop on water quality monitoring and assessment

Over 3 days, during a face-to-face workshop in Petten, the Netherlands, the authors of this paper discussed the use of CS for water quality monitoring. Experts from different world regions (Brazil, Cameroon, Costa Rica, Guatemala, Italy, Kenya, the Netherlands, Pakistan, Peru, Sierra Leone, and Switzerland), worked together to define the barriers that are still being faced to include citizen-generated data in national regional and global reporting. This team included civil servants, scientists, UN-officials, non-governmental organization, and the small-medium enterprise sector. The team worked together during to define what needs to be done to include CS in national regional and global reporting. The uniqueness of this assembly of roles, expertise and countries created the perfect environment for sharing experiences in order to reach the below perspectives. A full description of the workshop can be found in Chernov et al. (2024) .

3 Barriers to using citizen science water quality monitoring for SDG 6 reporting

This section presents the barriers faced in addition to those that are already well-described in the literature relating to reliability, precision and accuracy that lead to general “acceptance” and “usability” issues. In Figure 1 we summarize these barriers.

Figure 1 . Barriers to using citizen science water quality monitoring for SDG 6 reporting.

Awareness of the importance of good ambient water quality was highlighted as an important consideration. Globally, the disparity in access to safely managed drinking water is vast, ranging from over 90 per cent in Europe and North America to 31 per cent in Sub Saharan Africa ( World Health Organisation and United Nations Children's Fund, 2021 ). Furthermore, in 2021 66 countries reported that a proportion of their population relies directly on untreated surface water (rivers, lakes and ponds) for drinking water ( World Health Organisation and United Nations Children's Fund, 2021 ). This reliance on unimproved drinking water sources puts users at direct risk of the pollution and contamination events. In European countries, the perception of risk from water quality issues has been shown to vary according to age, education and engagement with environmental activities ( Skuras and Tyllianakis, 2018 ). In addition Europeans underestimate water use and their dependence on it ( Seelen et al., 2019 ).

To improve awareness, linking climate-related impacts due to changing hydrological patterns with incidents such as the recent Oder River ecological disaster ( Free et al., 2023 ), is important, and work that recognizes that local water quality actions have global climate implications are also welcomed ( Downing et al., 2021 ). Targeted awareness campaigns are also needed to promote public participation and to awareness across different social strata ( Skuras and Tyllianakis, 2018 ).

Long-term trends need long-term monitoring programs to identify them. Yet long-term and sustainable monitoring requires systems that can endure over time must consider the longevity of equipment, infrastructure, and methodologies employed in data collection to ensure continuous and uninterrupted monitoring. This of course must be embedded in an enabling environment that facilitates such monitoring programs. The challenge for many citizen scientist programs is that they are usually project-based and have a limited life span ( Blanco-Ramírez et al., 2023 ).

Data management of national agencies has been highlighted as a barrier to good water resource management ( UNEP, 2021 ). This hinders access to, and sharing of, data internally and externally within and between organizations, as well as the potential for these data to be properly assessed and made “decision-ready” for decision makers. Incorporating citizen-generated data into existing data management structures has rarely been considered and work is needed to optimize this process that accounts for the known limitations of citizen-generated data ( Quinlivan et al., 2020 ; Hegarty et al., 2021 ). Moreover, the use and integration of CS data into policy-making process has been identified as a motivational factor for citizens participation ( Stepenuck and Genskow, 2018 ; San Llorente Capdevila et al., 2020 ).

Securing adequate and stable funding sources is fundamental for sustaining data monitoring initiatives. This is true for national monitoring programs that struggle to maintain regular monitoring activities as well as for citizen scientists. For the latter, costs are presumed to be less than regulatory monitoring but there are questions over the costs involved when all factors are considered ( Alfonso et al., 2022 ). So, more cost-benefit analysis is needed that is broader in scope and accounts for benefits at scales beyond the local environment of the activity. Furthermore, other studies and projects in CS have pointed out the importance of partnerships and funding stability for long-term monitoring and citizens participation ( Deutsch and Ruiz-Córdova, 2015 ; San Llorente Capdevila et al., 2020 ).

4 Needs from a citizen scientist perspective

This section presents the needs from the perspective of citizen scientists to ensure the data generated can potentially contribute to SDG 6 monitoring. In the Figure 2 we summarize these needs accordingly.

Figure 2 . Needs of citizen scientists to contribute to water quality monitoring for national and/or SDG 6 reporting.

Improving the acceptability of citizen-generated data requires a multifaceted approach that ensures that citizen scientists are suitably engaged and trained to generate reliable data. Training as well as data quality control and assurance protocols are key components of monitoring strategies in CS programs ( Stepenuck and Genskow, 2018 ; San Llorente Capdevila et al., 2020 ). Continuous capacity building is needed to build technical capacity to apply the chosen methods and going on, to use and navigate through the changing technology. Reskilling and retooling for citizen scientists are essential to ensure they possess the necessary technical skills and knowledge to effectively engage with and adapt to evolving technologies in the field of CS. Empowering citizen scientists with technical capacity enhances their ability to contribute meaningfully to scientific projects, water stewardship initiatives, and advancements. It is essential to foster peer learning and collaboration by creating forums or community spaces where citizen scientists can share their experiences, best practices, and insights regarding the use of technology, and to reinforce sustained motivation action to address water quality issues with multiple stakeholders. In addition, it is essential to provide feedback mechanisms for citizen scientists to share their experiences with the technologies used ( San Llorente Capdevila et al., 2020 ).

Ensuring that the collected data lead to meaningful information is critical. Communication and feedback practices are also considered essential within CS projects ( San Llorente Capdevila et al., 2020 ). This includes the accessibility, comprehensibility, and meaningful interpretation of the data collected by citizen scientists ( Cooper et al., 2021 ). It involves presenting data in a format that can be easily understood and utilized by a diverse audience, including the public, researchers, policymakers, and other stakeholders. It is essential to produce tutorials, guides, or video demonstrations to enhance data usability by improving users' capabilities to navigate and interpret the data. Moreover, modes of localizing the data to ensure that language barriers do not hinder understanding and usability.

There is a need to mainstream CS into policies. The government, through its agencies, remains responsible for safeguarding the quality of water resources and must work in active partnership with all stakeholders involved in the gathering of data that will lead to more effective decision-making.

5 Discussion

Considering the challenges and the opportunities listed above, this section presents the output of the workshop in terms of what is needed to progress the empowerment of citizen scientists to improve their water quality.

Ultimately, it was identified that a simultaneous bottom-up/top-down approach is needed to ensure that citizen scientist initiatives can generate meaningful and useful data. During the workshop, it was noted that “Locally generated knowledge often has nowhere to go” and therefore data need a destination and purpose, and the information generated must be returned to inform local actions. Going further, “bottom-up” refers to the pressure generated by a growing awareness of the importance of water quality or “the discovery,” that leads to the initiation of CS activity and the generation of data. The top-down component refers to the creation or development of a framework that can accept these data and provides a “space” for them to feed into. Whether these CS data are considered in isolation or in combination with national authority data is an important consideration at the project design phase thereby ensuring that the necessary metadata, quality assurance and quality control protocols are available to maximize the potential of the data.

To foster the bottom-up pressure it was acknowledged that local motivated leaders, or a local water quality issue often serve as the “catalyst” and are key to initiate and sustain activities. Going beyond the initiation of activities, promotion of the expansion of CS from small catchment areas to large catchments and ultimately to national, regional, or global scales could promote the concept of “connecting to something bigger.” The SDGs offer such a framework to help upscale local activities. Both Sierra Leone and Zambia have incorporated citizen-generated data into their most recent SDG indicator 6.3.2 report to United Nations Environment Programme (UNEP, pers. comm. , March 2024). In addition, identifying and showcasing the success stories of CS initiatives, which can be shared through information platforms to reinforce people's awareness and other stakeholders' support would be a useful tool.

The reality that such significant water quality data gaps exist globally ( UNEP, 2021 ), and that national authorities struggle to collect sufficient data, presents an opportunity for citizen scientist-generated data to fill this void. For water quality monitoring, this applies to both spatial and temporal coverage. National agencies are unable to monitor remote locations regularly and are rarely able to collect data at requisite frequencies to gain a good understanding of the natural variation in water quality at a given location. Local citizens are by definition close to the water body, and can collect samples in response to target hydrological conditions such as peak flow conditions, or in response to an observed pollution incident ( Quinlivan et al., 2020 ; Hegarty et al., 2021 ).

Although many tools and approaches to citizen scientist monitoring exist, it was agreed that promotion of their use and improvements in their accessibility are needed. With advancements in information and communication technology resulting in ever cheaper and more powerful mobile devices, development of low-cost tools for accurately measuring of water variables in real-time should be encouraged.

The development of guidelines or standards to ensure the quality of CS data, to facilitate and enhance their uptake by official authorities would be of value. Bearing in mind the diversity of approaches available, the fitness for use and purpose concepts ( Bowser et al., 2020 ), guidelines on common elements such as quality assurance and quality control, as well as sample collection, and data management protocols would help to build confidence in the data produced ( Quinlivan et al., 2020 ).

6 Recommendations and way forward

Recommendations that were proposed included most notably developing a communication gateway that allows bi-directional data and information transferal between citizen scientists and civil servants/policy makers ( Figure 3 ). This would include linking citizen data to national, regional, and global reporting such as the SDGs, whilst simultaneously ensuring that information generated from citizen data is returned and contextualized at the local level into meaningful knowledge. Such a gateway could serve as a valuable resource for practitioners, researchers, policymakers, and the wider community, to improve and implement CS initiatives for national regional and global reporting. This platform could host and provide links to case studies, articles, guidelines, and other resources for easy access and reference and thereby serve “to share and showcase the great work out there” as highlighted during the workshop. Moreover, designing of visual infographics, videos, and interactive content is also important to present best practices in an engaging and easily palatable format. Care should be taken not to reinvent the wheel. The gateway should therefore make use of the many different existing platforms.

Figure 3 . Schematic of conceptual “Citizen Science Communication Gateway.”

In addition, it was acknowledged that the following points are important considerations:

1. Collaboration through partnerships is necessary, and through scaling-up and pooling of resources, effective implementation of CS can be achieved. For example, a partnership between academia, local authorities and citizens led to long term positive outcomes in Lebanon ( Baalbaki et al., 2019 ).

2. Further research is needed on participation incentives including different models of citizen participation such as direct payment or additional benefits. Mobile phones serve as useful tools for data collection and validation yet their cost to purchase and airtime can be prohibitve. In Kenya it was found that covering the cost of airtime significantly increases participation in a resource constrained setting ( Weeser et al., 2018 ). Performing a cost-benefit analysis that considers the costs and benefits of citizen engagement in water quality data collection and water resource management to explore the financial, social, and environmental benefits. As highlighted in Alfonso et al. (2022) the cost per measurement for CS data is higher than often expected when factoring in project set up and co-design, but a full cost-benefit analysis as for green/blue infrastructure in Sweden has to date not been undertaken for CS and water resource management ( Hamann et al., 2020 ).

3. The development of diverse funding streams is required that engage with stakeholders, and explore public-private partnerships which are key ingredients to maintain financial stability.

4. It is necessary to enhance the value of data obtained by non-specialized scientists to increase the impact of CS into the research works.

5. Water quality CS data should be verified and validated to ensure they are reliable and accurate before being integrated into the database. As part of the monitoring programme design, building collocated monitoring stations for both national agency and CS monitoring programmes will provide built in validation of data collected. In addition, as highlighted in Tunisia, data fusion techniques can provide confidence in CS data ( Jadeja et al., 2018 ).

It was noted during the workshop that “Potentially, we are all citizen scientists, and actors of change” yet the full potential of CS data for water resource management is yet to be realized. Testing its suitability through processes such as national, regional and/or global reporting frameworks such as for SDG 6, is one path that will help to determine the extent of this potential. Exploring what works and what does not, whilst simultaneously recognizing and accounting for national contexts is essential if acceptance and use of such an approach is to be normalized.

Data availability statement

The original contributions presented in the study are included in the article/supplementary material, further inquiries can be directed to the corresponding author.

Author contributions

SW: Conceptualization, Investigation, Writing—original draft. SB: Investigation, Writing—review & editing. SV: Investigation, Writing—review & editing. NM: Investigation, Writing—review & editing, Validation. HA: Investigation, Writing—review & editing. CT: Investigation, Writing—review & editing. MI: Investigation, Writing—review & editing. TA: Investigation, Writing—review & editing. EK: Investigation, Writing—review & editing. JC: Investigation, Writing—review & editing. MS: Investigation, Writing—review & editing. AG: Investigation, Writing—review & editing. SL: Conceptualization, Writing—review & editing. MJ: Conceptualization, Writing—review & editing.

The author(s) declare that no financial support was received for the research, authorship, and/or publication of this article.

Conflict of interest

JC was employed by Segura.

The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Publisher's note

All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article, or claim that may be made by its manufacturer, is not guaranteed or endorsed by the publisher.

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Keywords: water quality, citizen science, SDG 6, water quality data, sustainable development goals, policy

Citation: Warner S, Blanco Ramírez S, de Vries S, Marangu N, Ateba Bessa H, Toranzo C, Imaralieva M, Abrate T, Kiminta E, Castro J, de Souza ML, Ghaffar Memon A, Loiselle S and Juanah MSE (2024) Empowering citizen scientists to improve water quality: from monitoring to action. Front. Water 6:1367198. doi: 10.3389/frwa.2024.1367198

Received: 08 January 2024; Accepted: 26 March 2024; Published: 15 April 2024.

Reviewed by:

Copyright © 2024 Warner, Blanco Ramírez, de Vries, Marangu, Ateba Bessa, Toranzo, Imaralieva, Abrate, Kiminta, Castro, de Souza, Ghaffar Memon, Loiselle and Juanah. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY) . The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

*Correspondence: Stuart Warner, stuart.warner@un.org

Disclaimer: All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article or claim that may be made by its manufacturer is not guaranteed or endorsed by the publisher.

Retention ponds can deliver a substantial reduction in tire particle pollution

Retention ponds and wetlands constructed as part of major road schemes can reduce the quantities of tyre particles entering the aquatic environment by an average of 75%, new research has shown.

The study analysed samples collected alongside some of the busiest routes in South West England and the Midlands, many used by more than 100,000 vehicles each day.

Tyre particles were discovered in each of the 70 samples taken, confirming the findings of previous research which has shown them to pose a considerable environmental threat.

However, the presence of wetlands and retention ponds led to an average reduction of almost 75% in the mass of tyre wear particles being discharged to aquatic waters, thus providing protection for rivers and the ocean beyond.

The study also found that tyre wear particles significantly outweighed other forms of microplastics, such as plastic fibres and fragments, in the samples collected but that they were also removed in far greater quantities.

The researchers say that while the number of retention ponds and wetlands is quite small, in terms of the UK's entire road network, the study has international significance as to the most effective ways to mitigate against the potential impacts of tyre pollution on a global scale.

They have also recommended that the maintenance of retention ponds and wetlands should be considered a major priority so that their apparent benefits, when it comes to reducing the flow of tyre particles from roads to rivers, continue to be realised.

The research is published in the Environmental Science and Pollution Research journal, and was carried out by scientists from the University of Plymouth and Newcastle University. It was funded by UK National Highways.

Florence Parker-Jurd, Associate Research Fellow in the University of Plymouth's International Marine Litter Research Unit, is the study's lead author.

She said: "Retention ponds and wetlands are constructed as part of highways projects primarily to attenuate flow and prevent downstream flooding, but also to remove pollutants. This study set out to establish if these existing drainage measures in place along parts of the UK's strategic road network have the potential to halt the spread of tyre pollution. Our results are positive in that regard, and provide a much improved understanding on the extent and nature of tyre pollution. Similar drainage assets are used on a global scale; hence these results are of broad relevance to the management of tyre wear particle pollution."

Dr Geoff Abbott, Reader in Organic Geochemistry in the School of Natural and Environmental Sciences (SNES) at Newcastle University, has previously developed a breakthrough method using pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS) to detect tyre-derived particles in the environment.

He explained: "Py-GC-MS is a really productive approach that can unravel and quantify the monomeric components of microplastics in the environment. We used it to identify specific components of micro- and nanoplastics that can be unequivocally linked to vehicle tyre tread. That has enabled us to get hard numbers on the total amount of tyre wear particles that are collecting in the influent, effluent, and sediments of the retention ponds and wetlands in this study."

The new research builds on previous studies involving researchers from Plymouth and Newcastle showing that tyre particles can be transported directly to the ocean through the atmosphere or carried by rainwater into rivers and sewers.

Professor Richard Thompson OBE FRS, Head of the International Marine Litter Research Unit, is senior author on the current study.

He added: "Tyre particles are thought to be among the greatest sources of microplastic pollution worldwide. This finding suggests that existing features of the road network can halt their flow into rivers and seas. But the number of these features is small compared to the total road network and our earlier work has shown substantial quantities of tyre wear particles are dispersed by wind rater then water. Ultimately, we need to seek more systemic solutions perhaps via improved vehicle tyre design."

Professor Thompson is also currently leading the ongoing TYRE-LOSS project, which aims to highlight the effects of tyre pollution in the marine environment.

A study published by scientists involved in that project earlier this year also found that particles released into the environment from common road tyres should be treated as a "high concern" pollutant.

• Environmental Issues
• Air Pollution
• Environmental Awareness
• Air Quality
• Environmental Science
• Purple loosestrife
• Environmental impact assessment
• Air pollution
• Extinction event
• Global warming
• Climate engineering

Story Source:

Materials provided by University of Plymouth . Note: Content may be edited for style and length.

Journal Reference :

• Florence N. F. Parker-Jurd, Geoffrey D. Abbott, Bill Guthery, Gustav M. C. Parker-Jurd, Richard C. Thompson. Features of the highway road network that generate or retain tyre wear particles . Environmental Science and Pollution Research , 2024; DOI: 10.1007/s11356-024-32769-1

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