Community Water Systems Research Articles (Page 1)

Service area boundaries are the geographic delineation of a community water system’s (CWS) customer base. Lack of consistent and precise service area boundaries may affect how measures of water quality are geospatially assigned in academic or regulatory work, potentially hindering our ability to locate and accurately characterize disparities in drinking water provision. Though it is generally understood that more accurate boundaries would improve the analytical precision of drinking water quality analyses, it is unclear how the choice of boundary representations would impact conclusions of empirical analyses or the potential magnitude of bias. This paper aims to fill this gap by summarizing a set of novel drinking water quality metrics for arsenic, bacterial detection, disinfection byproduct formation, lead, nitrates, PFAS, and health-based violations of the Safe Drinking Water Act. We compare these drinking water measures across service area assignment methods including the use of county served, zip codes served, the EPIC/SimpleLab dataset, boundaries created by the U.S. Geologic Survey, and a national data layer produced by EPA’s Office of Research and Development. Conclusions regarding the presence of a disparity depend on the service area boundary selected for at least one demographic group for six of seven drinking water quality measures in this analysis. This paper helps to motivate the importance of producing, maintaining, and updating a high-quality, nationally consistent geodatabase of drinking water system service areas.

Short communication: simultaneous removal of co-occurring contaminants reduces drinking water-attributed cancer risk: A United States case study.

Preventing lead (Pb) contamination in rural community water systems in LMICs through analytical screening, policy and standards enforcement, and supply chain interventions

In the United States, most people get their drinking water from public water systems, whose quality is regulated by the Safe Drinking Water Act; however, an estimated 40 million people rely on unregulated private wells. In Massachusetts ∼500,000 people are estimated to rely on private wells, but records are incomplete, and public data on private well water quality is limited. We systematically explore the uncertainty and variability in estimated statewide health outcomes resulting from using different methods for estimating the number of users of private wells, groundwater arsenic concentrations, and arsenic toxicity. We use reported water quality data to approximate arsenic concentrations for private well users in the state and compare these methods to machine learning-based groundwater prediction maps. We compare the estimated cancer cases and adverse health effects for the different methods for assigning arsenic concentrations to wells, estimating locations of wells in Massachusetts, and the updated arsenic toxicity research. We find that updated arsenic toxicity research and uncertainty in groundwater arsenic concentrations have the greatest estimated impact on the cumulative number of cancer and noncancer outcomes. In Massachusetts, private well users have potentially 3-4 times greater risk of negative health impacts from arsenic compared to community water system users, with uncertainty largely driven by lack of contaminant concentration while in community water systems driven by uncertainty in toxicity.

Assessing the Impact of the Operational Context of Community Water Systems on Drinking Water Quality Violations: Trends in Health-Based Violations in Rural Alaska

Characterizing community water systems exposed to wildfire in the Western U.S.

Chronic low-level uranium (U) exposure through drinking water is a public health risk in the United States. Nearly two-thirds of community water systems, serving 320 million people, have detectable U levels, with 2% exceeding the EPA's maximum contaminant level of 30 μg/L. Ingested U accumulates in kidneys and is nephrotoxic at high levels. Uranium binds to proximal tubule cells, causing injury and interfering with kidney function. Epidemiological studies suggest that even low-level (<30 μg/L) of U exposure could damage kidneys. Current biomarkers, like urinary U levels, fail to indicate tissue-specific concentrations and metabolic interactions in kidneys. Fractionation of 238U/235U may potentially serve as a biomarker for the metabolic interaction of U with organs. Our experiments with mice showed changes in U isotopic composition (238U/235U expressed as δ238U) in organs after administering 50 mg/L U via drinking water for 2, 7, and 14 days. We found 235U enrichment in kidneys and bones, the target organs, while urine was enriched in 238U. Our results provide evidence of isotopic fractionation resulting from U accumulation in kidneys. Urinary U isotopic composition may, thus, provide a sensitive, noninvasive measurement of renal U bioaccumulation that could aid early detection of nephrotoxicity and prevention of irreversible kidney damage.

Arsenic in drinking water poses a threat to public health world-wide. In March 2001, the EPA revised the maximum contaminant level (MCL) for arsenic in drinking water downward from 50 µg/L to 10 µg/L and required all U.S. small community water systems (CWSs) and non-community water systems (NCWSs) to comply by 23 January 2006. Much of the financial burden associated with complying with and maintaining this new drinking water MCL was shouldered by local community governments. For example, the Walker River Paiute Tribe operated a CWS on the Walker River Paiute Indian Reservation that needed upgrading to meet the new arsenic MCL. In collaboration with the Walker River Paiute Tribe, we conducted a study to assess whether reducing the arsenic concentration in drinking water to meet the new MCL reduced the arsenic body burden in local community members who drank the water. Installing a drinking water treatment to remove arsenic dramatically reduced both the drinking water concentrations (to below the current EPA MCL of 10 µg/L) and the community members’ urinary concentrations of total As, AsIII, and AsV within a week of its full implementation. Additional assistance to small water systems to sustain new drinking water treatments may be warranted.

Several drinking water contaminants are known or suspected carcinogens; however, there are only a few investigations of drinking water exposures and ovarian cancer. We evaluated associations between regulated contaminants in community water systems (CWS) and ovarian cancer risk in the California Teachers Study, a prospective cohort of female California educators. Participants were cancer-free, without bilateral oophorectomy, living in California at baseline (1995-1996) with geocoded addresses linked to a CWS (N=91,127, 92%), with follow-up through 2020 (mean=19.0 years). Among participants with a residential duration at enrollment of at least 10 years, we computed 15-year (1990-2005) averages of log2-transformed arsenic, nitrate, total trihalomethanes (TTHM) (N=59,881), and uranium concentrations (N=56,314). We estimated hazard ratios (HRs, 95% CIs) for all epithelial ovarian cancers (n=424) and the high-grade serous histotype (n=203), using Cox proportional hazards regression, adjusting for age, body mass index, menopause status, oral contraceptive use, and parity. We evaluated the mixture effect (per IQR in log2 concentrations), using quantile-based g-computation. Almost all women (>99%) had average exposures below regulatory limits for all contaminants. In single contaminant analyses, a doubling in average uranium concentrations was associated with all ovarian cancer (HRperlog2=1.09, CI 1.02-1.16), whereas a doubling in nitrate was associated with the high-grade serous histotype (HRperlog2=1.09, CI 1.02-1.17). Findings were similar in models adjusted for other contaminants. We observed positive but imprecise associations for arsenic and TTHM in single-contaminant and contaminant-adjusted analyses. HRs per increase in the mixture were 1.39 (1.00, 1.94) and 1.75 (1.09, 2.83), for all ovarian cancer and the high-grade serous histotype, respectively. Uranium was the largest contributor (55%) to the mixture effect for all ovarian cancer, and nitrate was the largest contributor (46%) for the high-grade serous histotype. Novel associations between drinking water contaminants and ovarian cancer risk at levels below regulatory limits warrant further investigation. https://doi.org/10.1289/EHP16582.

The variability in the nontarget chemical composition of tap water from 120 households and 15 brands of retail water was analyzed during two seasons. Fifteen households in eight separate community water systems were evaluated with the goal of identifying compounds with high within-source variability and investigating potential origins of the observed variation. High resolution mass spectrometry with liquid and gas chromatography was implemented and 10 chemical features from each water system with the highest coefficient of variation and a tentative library match were prioritized for investigation. This prioritization filter reduced the number of considered features from the 16,929 originally isolated to 282. High confidence structural annotations could be assigned to 134 compounds, which were then categorized based on plausible contaminant inputs. The most common source category was plastic (potentially originating from piping, fittings or packaging), with 47/50 of the GC compounds and 22/40 of the LC compounds having possible plastic-related origins. Other important source categories included other distribution system components (polychlorinated biphenyls, historically used in caulking), disinfection byproducts (trihalomethanes), and contaminants present in source waters at varying levels (sucralose, PFAS). The findings highlight the diverse constituents introduced into drinking water from the distribution system and the importance of assessing chemical exposures via drinking water at the point of use.

Groundwater is a critical drinking water source in arid regions globally, where reliance on groundwater is highest. However, disparities in groundwater availability, access, and quality pose challenges to water security. This case study employs geostatistical tools, multivariate regression, and clustering analysis to examine the intersection of groundwater level changes (availability), socioeconomic and regulatory factors (access), and nitrate and arsenic contamination (quality) across 1881 groundwater-supplied drinking water service areas in Arizona. Groundwater availability declined over 20-year and 10-year periods, particularly outside designated management areas, with mean annual decline rates ranging from −15.97 to −0.003 m/year. In contrast, increases (0.003 to 13.41 m/year) were concentrated in urban and managed areas. Karst aquifers show long-term resilience but short-term vulnerability. Non-designated areas exhibit mixed effects, reflecting variable management effectiveness. Disparities in groundwater access emerge along various socioeconomic and regulatory lines. Communities with higher Black populations are twice as likely (OR = 2.01, p &lt; 0.001) to experience groundwater declines, while Hispanic/Latino communities have lower depletion risks (OR = 0.92, p &lt; 0.001). Tribal oversight significantly reduces groundwater decline risk (OR = 0.62, p &lt; 0.001), whereas state–primacy areas show mixed effects. Higher female populations correlate with increased groundwater declines, while older populations (65+) experience greater stability. Married-family households and institutional housing are associated with greater declines. Migrant worker housing shows protective effects in long-term models. Rising groundwater levels are associated with higher nitrate and arsenic detection, reinforcing recharge-driven contaminant mobilization. Nitrate exceedance (OR = 1.05) responds more to short-term groundwater changes, while arsenic exceedance persists over longer timescales (OR = 1.01–1.05), reflecting their distinct hydrogeochemical behaviors. Community water systems show higher pollutant detection rates than domestic well areas, suggesting monitoring and infrastructure differences influence contamination patterns. Tribal primacy areas experience lower groundwater declines but show mixed effects on water quality, with reduced nitrate exceedance probabilities; yet they show variable arsenic contamination patterns, suggesting that governance influences availability and contamination dynamics. These findings advance groundwater sustainability research by quantifying disparities across multiple timescales and socio-hydrogeological drivers of groundwater vulnerability. The results underscore the need for expanded managed aquifer recharge, targeted regulatory interventions, and strengthened Tribal water governance to reduce inequities in availability, access, and contamination risk to support equitable and sustainable groundwater management.

BackgroundThe Centers for Disease Control and Prevention (CDC) reports that water fluoridation is among the ten greatest public health achievements of the 20th Century. Tooth decay (TD) prevention and neurodevelopmental disorder (ND) risk were assessed in relation to childhood water fluoridation exposure.MethodsThis longitudinal cohort study examined the Independent Healthcare Research Database (IHRD) composed of prospectively collected healthcare data from the Florida Medicaid system for the period 1990–2012, using logistic and frequency statistical modeling (with adjustment for covariates). A cohort of 73,254 children continuously enrolled for their first 10 years of life was examined. The yearly percentage of persons in Florida receiving fluoridated water exposure from community water systems was examined by county. The number of children diagnosed with TD, autism spectrum disorder (ASD), attention deficit-hyperactivity disorder (ADHD), intellectual disability (ID), and specific delays in development (SDD) was evaluated.ResultsFluoride exposure in the year of birth, statistically significantly and dose-dependently, slightly reduced the risk of TD, and, separately, slightly increased the risk of ASD, ADHD, ID, and SDD. During the first 10 years of life, children who were fluoride-exposed as compared to unexposed were at significantly lower risk for TD, and, separately, at significantly greater risk for ASD, ID, and SDD.ConclusionsFindings from the present study, coupled with previous studies, suggest new risk/benefit analyses of water fluoridation should be undertaken.

Abstract Very small drinking water systems in the United States can face challenges in complying with the Safe Drinking Water Act, resulting in a need to improve existing infrastructure. This study applied a triple bottom-line approach to compare modeled health, environmental, and economic impacts of improving existing centralized water treatment systems to using point-of-use/point-of-entry (POU/POE) devices in four very small community water systems (CWS) serving 40–450 people. We found that POU/POE systems could be implemented 1–3 years faster than centralized improvements and achieve higher removal efficiencies (up to 99% removal for arsenic, compared to 80% for some centralized options), resulting in larger decreases in human exposure to arsenic or nitrate. Treatment options using adsorptive media or ion exchange resins had larger overall environmental impacts than reverse osmosis devices, and the total 30 year cost of POUs/POEs were more expensive in 3 of the 4 modeled systems than centralized improvements due to high replacement frequencies and populations. An ‘ideal’ option in each CWS was not selected; rather, we contextualized our results as tradeoffs.

Groundwater is a vital drinking water source, especially in arid regions, sustaining both urban and rural populations. Its quality is influenced by natural (hydrogeological) and human-driven (demographic, policy) factors, which may pose significant public health risks, especially for communities relying on unregulated water supplies. This study addresses critical gaps by examining groundwater vulnerability and contamination disparities, emphasizing their implications for public health and equitable resource management. It analyzes the impact of socio-hydrogeological factors on arsenic and nitrate levels in groundwater-supplied systems in Arizona, U.S. Methods include spatial analysis, ANOVA, multivariate regression, and cluster analysis. Significant disparities in arsenic and nitrate contamination, including exceedances of regulatory limits, were observed across supply types, aquifer characteristics, jurisdictional oversights, and groundwater management areas. Domestic wells and community water systems showed distinct contamination risks. Groundwater vulnerability was influenced by geological differences (karst vs. alluvial aquifers) and regulatory oversight, with Tribal and State systems facing unique challenges and resource needs. Socioeconomic disparities were evident, with minority communities, institutional facilities, rural areas, and specific housing types disproportionately exposed to higher contaminant levels. These findings unveil the intersection of race, socioeconomic status, and public health risks, offering an adaptable framework for addressing similar groundwater challenges in arid and semi-arid regions globally. This study is innovative in its focus on policy distinctions between private and regulated wells, karst and alluvial aquifers, and State and Tribal jurisdictions. It emphasizes the need for targeted vulnerability assessments and remediation strategies that integrate geological, hydrological, and regulatory factors to address risk disparities in vulnerable communities. These environmental inequities underscore the urgent need for stronger regulations and strategic resource allocation to support marginalized communities. The study recommends enhancing monitoring protocols, prioritizing resource distribution, and implementing targeted policy interventions to ensure equitable and sustainable access to safe drinking water in arid regions.

We present a novel report of abundance of halophilic Vibrio alginolyticus with thermotolerant and enterotoxigenic characteristics from community water system of an inland-focus of India causing diarrheal outbreak as an index pathogen. Though, Vibrio alginolyticus causing diarrhea after exposure to marine water and consumption of seafood was reported globally, its existence in non-saline drinking-water sources with pathogenic viability was unknown. A 'matched-pair-case-control' study identified the primary source of V. alginolyticus infection as 'tap-water' distributed by the municipality, used for drinking (MOR: 8.33; 95% CI 2.51-27.6) and household chores (MOR: 3.75; 95% CI 1.24-11.3). Cardinal toxin gene 'tdh' and other pathogenicity markers viz.tlh, vppC, toxR, VPI, T3SS1 and sxt were detected in V. alginolyticus isolates. Expression potential of the hemolytic genes are demonstrated by hemolysis assay and transcriptome analysis. Altogether 30.55% of isolates exhibited strong hemolytic potential in vitro. RT-PCR revealed uninterrupted virulence gene expression in outbreak strains under heat stress. Surprisingly, ~ 100% of V. alginolyticus from the outbreak focus were sensitive/partially sensitive to all group of antibiotics except β-lactums, carbapenem and quinolones. High drug-sensitivity suggested lack of previous human gut exposure and indicated a fresh dissemination from the environmental niche to the community domain. The maximum likelihood phylogeny depicted multiple clades in V. alginolyticus strains from Pan India sources. Isolated outbreak strains shared common ancestry with the strains from nearby riverine system, a source of 'drinking water' supplied to the affected community, confirming its environmental origin. V. alginolyticus, traditionally a fish-pathogen, is steadily gaining an emerging epidemiological relevance alongside other waterborne diarrheagenic bacteria and its 'thermotolerant' attribute poses additional threat under the canvas of climate change.

Epidemiologic and animal studies both support relationships between exposures to per- and polyfluoroalkyl substances (PFAS) and harmful effects on the immune system. Accordingly, PFAS have been identified as potential environmental risk factors for adverse COVID-19 outcomes. Here, we examine associations between PFAS contamination of U.S. community water systems (CWS) and county-level COVID-19 mortality records. Our analyses leverage two datasets: one at the subnational scale (5371 CWS serving 621 counties) and one at the national scale (4798 CWS serving 1677 counties). The subnational monitoring dataset was obtained from statewide drinking monitoring of PFAS (2016-2020) and the national monitoring dataset was obtained from a survey of unregulated contaminants (2013-2015). We conducted parallel analyses using multilevel quasi-Poisson regressions to estimate cumulative incidence ratios for the association between county-level measures of PFAS drinking water contamination and COVID-19 mortality prior to vaccination onset (Jan-Dec 2020). In the primary analyses, these regressions were adjusted for several county-level sociodemographic factors, days after the first reported case in the county, and total hospital beds. In the subnational analysis, detection of at least one PFAS over 5 ng/L was associated with 12% higher [95% CI: 4%, 19%] COVID-19 mortality. In the national analysis, detection of at least one PFAS above the reporting limits (20-90 ng/L) was associated with 13% higher [95% CI: 8%, 19%] COVID-19 mortality. Our findings provide evidence for an association between area-level drinking water PFAS contamination and higher COVID-19 mortality in the United States. These findings reinforce the importance of ongoing state and federal monitoring efforts supporting the U.S. Environmental Protection Agency's 2024 drinking water regulations for PFAS. More broadly, this example suggests that drinking water quality could play a role in infectious disease severity. Future research would benefit from study designs that combine area-level exposure measures with individual-level outcome data.

Key TakeawaysIn the United States, all community and nontransient noncommunity water systems are required to submit an inventory describing the location and makeup of all service lines in their service areas.While the material can be designated as lead, galvanized requiring replacement, nonlead, or unknown, the last two designations require additional steps to be taken in the proposed Lead and Copper Rule Improvements (LCRI).Some utilities have few or no lead service lines, and this inventory requirement, issued by the US Environmental Protection Agency (EPA), may be burdensome to those utilities.This article demonstrates the methodology in EPA's proposed LCRI for verification of construction material, and an alternate validation procedure is proposed.

Objectives. To quantify the impact of droughts on drinking water arsenic and nitrate levels provided by community water systems (CWSs) in California and to assess whether this effect varies across sociodemographic subgroups. Methods. I integrated CWS characteristics, drought records, sociodemographic data, and regulatory drinking water samples (n = 83 317) from 2378 water systems serving 34.8 million residents from 2007 to 2020. I analyzed differential drought effects using fixed-effect regression analyses that cumulatively accounted for CWS-level trends, income, and agricultural measures. Results. CWSs serving majority Latino/a communities show persistently higher and more variable drinking water nitrate levels. Drought increased nitrate concentrations in majority Latino/a communities, with the effect doubling for CWSs with more than 75% Latino/a populations served. Arsenic concentrations in surface sources also increased during drought for all groups. Differential effects are driven by very small (< 500) and privately owned systems. Conclusions. Impending droughts driven by climate change may further increase drinking water disparities and arsenic threats. This underscores the critical need to address existing inequities in climate resilience planning and grant making. (Am J Public Health. 2024;114(9):935-945. https://doi.org/10.2105/AJPH.2024.307758).

The United States Environmental Protection Agency (USEPA) regulates over 80 contaminants in community water systems (CWS), including those relevant to infant health outcomes. Multi-cohort analyses of the association between measured prenatal public water contaminant concentrations and infant health outcomes are sparse in the US. Our objectives were to (1) develop Zip Code Tabulation Area (ZCTA)-level CWS contaminant concentrations for participants in the Environmental Influences on Child Health Outcomes (ECHO) Cohort and (2) evaluate regional, seasonal, and sociodemographic inequities in contaminant concentrations at the ZCTA-level. The ECHO Cohort harmonizes data from over 69 extant pregnancy and pediatric cohorts across the US. We used CWS estimates derived from the USEPA's Six-Year Review 3 (2006-2011) to develop population-weighted, average concentrations for 10 contaminants across 7640 ZCTAs relevant to the ECHO Cohort. We evaluated contaminant distributions, exceedances of regulatory thresholds, and geometric mean ratios (with corresponding percent changes) associated with ZCTA sociodemographic characteristics via spatial lag linear regression models. We observed significant regional variability in contaminant concentrations across the US. ZCTAs were most likely to exceed the maximum contaminant level for arsenic (n = 100, 1.4%) and the health-protective threshold for total trihalomethanes (n = 3584, 64.0%). A 10% higher proportion of residents who were American Indian/Alaskan Native and Hispanic/Latino was associated with higher arsenic (11%, 95% CI: 7%, 15%; and 2%, 95% CI: 0%, 3%, respectively) and uranium (15%, 95% CI: 10%, 21%; and 9%, 95% CI: 6%, 12%, respectively) concentrations. Nationwide epidemiologic analyses evaluating the association between US community water system contaminant concentration estimates and associated adverse birth outcomes in cohort studies are sparse because public water contaminant concentration estimates that can be readily linked to participant addresses are not available. We developed Zip Code Tabulation Area (ZCTA)-level CWS contaminant concentrations that can be linked to participants in the Environmental Influences on Child Health Outcomes (ECHO) Cohort and evaluated regional, seasonal, and sociodemographic inequities in contaminant concentrations for these ZCTAs. Future epidemiologic studies can leverage these CWS exposure estimates in the ECHO Cohort to evaluate associations with relevant infant outcomes.

Public Community Water System Expenditures Across the Downstate Region of Illinois