Climate hazards expose distinct compliance vulnerabilities in US drinking water systems
1Department of Community, Environment and Policy, Mel & Enid Zuckerman College of Public Health, University of Arizona, Tucson, AZ, USA.
Research Square
|April 27, 2026
Summary
Climate extremes like heavy rain and heat impact drinking water safety. Extreme precipitation significantly increases violations, while heat affects microbial contamination, highlighting the need for climate-aware monitoring.
Area of Science:
- Environmental Science
- Public Health
- Water Resource Management
Background:
- Climate extremes pose a significant threat to the reliability and safety of drinking water systems.
- The specific pathways through which climate hazards affect drinking water quality and regulatory compliance are not well understood at a national scale.
Purpose of the Study:
- To investigate the association between climate extremes (extreme precipitation, heat intensity, wildfire smoke) and the risk of Safe Drinking Water Act violations.
- To identify the specific contaminant categories and water system characteristics most vulnerable to climate-related disruptions.
Main Methods:
- Linked monthly data on extreme precipitation, heat intensity, and wildfire smoke PM2.5 with Safe Drinking Water Act violation data for 56,351 community water systems from 2006-2020.
- Analyzed violation risks across twelve contaminant categories, differentiating by system type (e.g., surface water, small systems).
Main Results:
- Extreme precipitation was linked to increased risks (8-13%) of turbidity, coliform, disinfection byproduct, and treatment-technique violations, particularly in surface-water and smaller systems.
- Increased heat intensity correlated with a higher risk of Escherichia coli (E. coli) violations (~2.6% per °C), though the causal pathway requires further investigation.
- Associations between wildfire smoke and violations were weak and inconsistent, suggesting a provisional link at best.
Conclusions:
- Findings demonstrate a hierarchy of climate hazard impacts: precipitation effects are robust, heat effects are specific to microbial contaminants, and smoke effects are provisional.
- Advocates for climate-responsive monitoring strategies, with tailored triggers based on the strength of evidence for each hazard.
- Recommends enhanced post-precipitation monitoring, especially for smaller drinking water systems, to mitigate climate-related risks.
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