EPA health-based violations are the most serious type of drinking water compliance issue. They occur when water exceeds Maximum Contaminant Levels for substances like lead, arsenic, nitrates, or bacteria. Using EPA SDWIS data, we identified the 25 counties with the most recorded health-based violations.
These violations do not always mean water is currently unsafe — many are resolved quickly. But high violation counts indicate systemic challenges with water treatment, infrastructure, or monitoring.
The 25 Counties with the Most Water Violations
These counties have the highest recorded health-based violation counts:
Important
When a Tier 1 health-based violation occurs (acute risk like E. coli), water systems must notify customers within 24 hours. For non-acute violations, notification is required within 30 days. Always read notices from your water utility.
Methodology
Violation data comes from the EPA Safe Drinking Water Information System (SDWIS), accessed through the ECHO API. Health-based violations include Maximum Contaminant Level (MCL) violations and Treatment Technique (TT) violations that pose a health risk. Violation counts are aggregated from all public water systems serving each county. Counties are ranked by total health-based violation count in descending order.
Data source: U.S. Environmental Protection Agency, Safe Drinking Water Information System (SDWIS) Federal Reporting Services, accessed via ECHO API. All figures are estimates based on publicly available compliance data and may differ from other published analyses due to methodology differences.