Compound climate hazards amplify health-based drinking water violations in U.S. community water systems

• In Event: Environmental Sociology Section Roundtables
  In Refereed Roundtable (60 minute): Table 10: From Environmental Risk to Social Response

Abstract

Climate change is intensifying precipitation extremes, heat and drought, often in combinations that can disproportionately disrupt water quality and treatment performance.

However, evidence on drinking water safety largely quantifies single hazards or additive effects, limiting understanding of how short-run and seasonal climate stressors jointly shape compliance risk - and whether these risks are concentrated in socially vulnerable communities and specific land-use contexts.

Here, I assemble a national longitudinal dataset linking >6 million Safe Drinking Water Act (SDWA) enforcement records for community water systems (CWSs) from 1975–2025 to system service-area socio-demographics and socioeconomics, land-use characteristics and climate indicators measured at multiple time scales. The primary outcome is health-based violations, including exceedances for microorganisms and other regulated contaminants. Climate exposures capture acute and cumulative stressors: total precipitation and maximum temperature in the previous 10 days, and three-month averages of precipitation, maximum temperature and a drought index.

I estimate nonlinear multi-stressor response surfaces and interaction effects using a fine-tuned supervised learning model, and quantify main and joint contributions with grouped SHAP and Sobol sensitivity indices. To evaluate robustness and interrogate mechanisms, I compare these estimates with structural equation models that decompose direct climate effects and indirect effects mediated by social vulnerability and land-use/environmental conditions.

This framework identifies conditions under which precipitation, heat and drought act multiplicatively rather than additively, isolates subgroup-specific interactions, and provides empirically grounded targets for climate adaptation and drinking water governance.

Author

• Liangfei Ye, Texas A&M University (will start in August 2025)