Some counties face a dangerous combination of low water quality scores and active health violations. These are the most at-risk water supplies in America — places where water systems struggle with both compliance and infrastructure challenges.
Using EPA SDWIS data, we identified the 25 counties with the lowest water quality scores that also have at least one recorded health-based violation.
The Most At-Risk Water Supplies by County
These counties have the lowest water quality scores combined with active violation records:
Important
If your county appears on this list, request your water system's Consumer Confidence Report (CCR) and consider independent water testing. Many violations are resolved quickly, but chronic issues require attention.
Methodology
Counties are ranked by water quality score in ascending order, filtered to include only those with at least one recorded health-based violation. Water quality scores use percentile-rank methodology based on EPA SDWIS data. Letter grades map to score ranges: A (90-100), B (75-89), C (60-74), D (40-59), F (0-39).
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.