Dataset Information

National trends in drinking water quality violations.

ABSTRACT: Ensuring safe water supply for communities across the United States is a growing challenge in the face of aging infrastructure, impaired source water, and strained community finances. In the aftermath of the Flint lead crisis, there is an urgent need to assess the current state of US drinking water. However, no nationwide assessment has yet been conducted on trends in drinking water quality violations across several decades. Efforts to reduce violations are of national concern given that, in 2015, nearly 21 million people relied on community water systems that violated health-based quality standards. In this paper, we evaluate spatial and temporal patterns in health-related violations of the Safe Drinking Water Act using a panel dataset of 17,900 community water systems over the period 1982-2015. We also identify vulnerability factors of communities and water systems through probit regression. Increasing time trends and violation hot spots are detected in several states, particularly in the Southwest region. Repeat violations are prevalent in locations of violation hot spots, indicating that water systems in these regions struggle with recurring issues. In terms of vulnerability factors, we find that violation incidence in rural areas is substantially higher than in urbanized areas. Meanwhile, private ownership and purchased water source are associated with compliance. These findings indicate the types of underperforming systems that might benefit from assistance in achieving consistent compliance. We discuss why certain violations might be clustered in some regions and strategies for improving national drinking water quality.

SUBMITTER: Allaire M

PROVIDER: S-EPMC5834717 | biostudies-literature | 2018 Feb

REPOSITORIES: biostudies-literature

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National trends in drinking water quality violations.

Allaire Maura M Wu Haowei H Lall Upmanu U

Proceedings of the National Academy of Sciences of the United States of America 20180212 9

Ensuring safe water supply for communities across the United States is a growing challenge in the face of aging infrastructure, impaired source water, and strained community finances. In the aftermath of the Flint lead crisis, there is an urgent need to assess the current state of US drinking water. However, no nationwide assessment has yet been conducted on trends in drinking water quality violations across several decades. Efforts to reduce violations are of national concern given that, in 201 ...[more]

PMID: 29440421

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Project description:Excess nitrate in drinking water is a human health concern, especially for young children. Public drinking water systems in violation of the 10 mg nitrate-N/L maximum contaminant level (MCL) must be reported in EPA's Safe Drinking Water Information System (SDWIS). We used SDWIS data with random forest modeling to examine the drivers of nitrate violations across the conterminous U.S. and to predict where public water systems are at risk of exceeding the nitrate MCL. As explanatory variables, we used land cover, nitrogen inputs, soil/hydrogeology, and climate variables. While we looked at the role of nitrate treatment in separate analyses, we did not include treatment as a factor in the final models, due to incomplete information in SDWIS. For groundwater (GW) systems, a classification model correctly classified 79% of catchments in violation and a regression model explained 43% of the variation in nitrate concentrations above the MCL. The most important variables in the GW classification model were % cropland, agricultural drainage, irrigation-to-precipitation ratio, nitrogen surplus, and surplus precipitation. Regions predicted to have risk for nitrate violations in GW were the Central California Valley, parts of Washington, Idaho, the Great Plains, Piedmont of Pennsylvania and Coastal Plains of Delaware, and regions of Wisconsin, Iowa, and Minnesota. For surface water (SW) systems, a classification model correctly classified 90% of catchments and a regression model explained 52% of the variation in nitrate concentration. The variables most important for the SW classification model were largely hydroclimatic variables including surplus precipitation, irrigation-to-precipitation ratio, and % shrubland. Areas at greatest risk for SW nitrate violations were generally in the non-mountainous west and southwest. Identifying the areas with possible risk for future violations and potential drivers of nitrate violations across U.S. can inform decisions on how source water protection and other management options could best protect drinking water.

Project description:In 1974, the United States established the Safe Drinking Water Act (SDWA) to protect consumers from potential exposure to drinking water contaminants associated with health risks. Each contaminant is assigned a health-based standard meant to reflect the maximum level at which an adverse human health outcome is unlikely; measurements beyond that level have greater potential to result in adverse health outcomes. Although there is extensive research on human health implications following water contaminant exposure, few studies have specifically examined associations between fetal health and municipal drinking water violations. Therefore, the objective of this study is to assess whether SDWA drinking water violations are associated with fetal health outcomes, including preterm birth (PTB), low birth weight (LBW), and term-low birth weight (tLBW), in the Commonwealth of Virginia. Singleton births (n = 665,984) occurring between 2007 and 2015 in Virginia were geocoded and assigned to a corresponding estimated water service area. Health-based (HB) and monitoring and reporting (MR) violations for 12 contaminants were acquired from the US EPA Safe Drinking Water Information System, with exposure defined at the approximate service area level to limit exposure misclassification. A logistic regression model for each birth outcome assessed potential relationships with SDWA violations. When examining the association between individual MR violations and birth outcomes, Nitrate-Nitrite (OR = 1.10; 95% CI = 1.02, 1.18, P = 0.01) was positively associated with PTB and the total coliform rule was negatively associated with tLBW (OR = 0.93; 95% CI = 0.87, 1.00, P = 0.04). These findings indicate that a lack of regular monitoring and reporting by water providers (resulting in monitoring and reporting violations) may be concealing health-based violations as these health concerns cannot be revealed without testing, suggesting a need for additional technical, managerial, and financial support to enable often-underfunded water systems to adhere to monitoring and reporting requirements meant to protect public health.

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Dataset Information

National trends in drinking water quality violations.

Publications

National trends in drinking water quality violations.

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