Inequities in Drinking Water Quality Among Domestic Well Communities and Community Water Systems, California, 2011‒2019

Abstract

Objectives. To evaluate universal access to clean drinking water by characterizing relationships between community sociodemographics and water contaminants in California domestic well areas (DWAs) and community water systems (CWSs). Methods. We integrated domestic well locations, CWS service boundaries, residential parcels, building footprints, and 2013–2017 American Community Survey data to estimate sociodemographic characteristics for DWAs and CWSs statewide. We derived mean drinking and groundwater contaminant concentrations of arsenic, nitrate, and hexavalent chromium (Cr[VI]) between 2011 and 2019 and used multivariate models to estimate relationships between sociodemographic variables and contaminant concentrations. Results. We estimated that more than 1.3 million Californians (3.4%) use domestic wells and more than 370 000 Californians rely on drinking water with average contaminant concentrations at or above regulatory standards for 1 or more of the contaminants considered. Higher proportions of people of color were associated with greater drinking water contamination. Conclusions. Poor water quality disproportionately impacts communities of color in California, with the highest estimated arsenic, nitrate, and Cr(VI) concentrations in areas of domestic well use. Domestic well communities must be included in efforts to achieve California’s Human Right to Water. (Am J Public Health. 2022;112(1):88–97. https://doi.org/10.2105/AJPH.2021.306561 )

High-resolution gridded estimates of population sociodemographics from the 2020 census in California

“…Producing high-resolution CA-POP grids for various demographic variables estimated in the 2020 census, including racial and ethnic subgroups, can serve as a resource for studies that seek to evaluate these communities. A precursor to the 2020 CA-POP grids developed by the authors, based on 2017 American Community Survey block group and 2010 block source zones, were employed by Casey et al ( 2021) [ 38 ] to assess social inequalities in residential proximity to large methane-emitting sites and in Pace et al ( 2022) [ 39 ] to estimate racial/ethnic inequalities in estimated drinking water concentrations of arsenic, nitrate, and hexavalent chromium from community water systems and areas of potentially high domestic well prevalence, demonstrating the utility of CA-POP for environmental equity studies. As more socio-demographic variables are released by future U.S. Census Bureau’s American Community Surveys from the U.S. Census Bureau, additional grids based on these block group-level values may be produced and uploaded to the public CA-POP repository (github.com/njdepsky/CA-POP).…”

The Drinking Water Tool: A Community-Driven Data Visualization Tool for Policy Implementation

“…Additionally, communities served by domestic wells often face significant water quality challenges compared to those served by community water systems (CWSs). It is estimated that 1.3 million Californians rely on private domestic wells [15], which commonly serve rural, agricultural, and socioeconomically disadvantaged communities [16]. A recent statewide environmental justice study in California found that mean arsenic, nitrate and hexavalent chromium levels exceeded their respective MCLs for a greater proportion of people who used a domestic well compared to those who used a community water system, and that poor water quality in domestic well areas disproportionately impacted Latinx and communities of color [15].…”

“…It is estimated that 1.3 million Californians rely on private domestic wells [15], which commonly serve rural, agricultural, and socioeconomically disadvantaged communities [16]. A recent statewide environmental justice study in California found that mean arsenic, nitrate and hexavalent chromium levels exceeded their respective MCLs for a greater proportion of people who used a domestic well compared to those who used a community water system, and that poor water quality in domestic well areas disproportionately impacted Latinx and communities of color [15]. As these contaminants pose cancer and non-cancer health risks [17], such groundwater contamination threats can contribute to cumulative exposures from multiple chemical stressors and disproportionate health burdens among the impacted communities [11,12,14].…”

“…Meanwhile, the State Board has developed tools focused on domestic wells: the 2021 Aquifer Risk Map [22] and the GAMA program's Domestic Well Water Quality Tool [23], both released in 2021 as part of the 2021 Drinking Water Needs Assessment [24] do not include CWSs. Presently, these State Board tools consider ambient groundwater quality from monitoring wells, not treated water delivered by community water systems, and give an incomplete picture of water quality differences in domestic well areas compared to those served by CWSs [15]. A final tool under development during the same period is the DWR's Drought and Water Shortage Risk Explorer, which contains data layers related to drought risk and is designed to help smaller water systems and selfsupplied communities (e.g., communities served by domestic wells) to better understand their potential drought vulnerability [25].…”

The Human Right to Water: A 20-Year Comparative Analysis of Arsenic in Rural and Carceral Drinking Water Systems in California

“…1 In the United States, exposure to arsenic contamination in drinking water disproportionately impacts small, groundwater-reliant communities and communities of color. 2 , 3 These inequities are driven by a combination of natural, built, and sociopolitical factors. 4 The United Nations calls upon states to especially safeguard the right to safe water for groups that may face difficulties exercising this right, such as incarcerated people.…”