Disparities in drinking water quality: evidence from California

Abstract Reducing disparities in drinking water quality is a state-level priority in California, yet targeting communities for assistance is hindered by the lack of empirical evidence regarding populations disproportionately affected. The study addresses this gap by analyzing drinking water quality violations and identifying the types of communities disproportionately burdened by water contaminants. Using a sample of 1,710 Community Water Systems (CWSs) and probit regression models, we analyzed the likelihood of violation as a function of low-income, minority groups, and vulnerable populations. Results indicate that environmental justice concerns are prevalent. Low-income communities and minority groups (Hispanics and non-Whites) face greater likelihood of water quality violations. Low-income communities are 1.77% more likely to have any health-related violations. Severely disadvantaged communities face greater likelihood (3.44%) of water quality violations. Tribal water systems are 2% more likely to violate the Total Coliform Rule. Children aged five and under are 3% more likely to be exposed to health-based water quality violations. Failure to address prior violations leads to greater likelihood (38.94%) of future violations, while large utility systems and purchased water sources have the propensity to reduce violations. Overall, these findings can guide policy decisions to prioritize assistance to communities disproportionately impacted by poor water quality.