Water quality in the United States is not uniform. A glass of tap water in Hawaii and a glass in Texas may tell very different stories about treatment, infrastructure, and regulatory enforcement. Using EPA Safe Drinking Water Information System (SDWIS) data and UCMR 5 PFAS testing results, SafeWater tracks water quality for every state.
How We Rank States
Our state rankings are based on three core metrics:
- Health-Based Violation Rate: percentage of community water systems (CWSs) with at least one MCL exceedance in the past 5 years
- Monitoring & Reporting Compliance: utilities that fail to submit required testing results
- PFAS Contamination: percentage of systems with any PFAS detected and any MCL exceedance per UCMR 5
Explore the interactive data: SafeWater State Rankings →
States with the Most Violations
Historically, states with the highest rate of health-based violations include Texas, Pennsylvania, Florida, and California. These states have large numbers of small water systems that lack resources for adequate treatment. Small systems (serving under 500 people) account for the vast majority of EPA violations nationwide.
PFAS Contamination by State
Per EPA UCMR 5 and EWG data, the states with the highest PFAS contamination include:
- California: high industrial PFAS use and large population tested
- Pennsylvania: legacy manufacturing and military base contamination
- Michigan: extensive groundwater contamination
- Massachusetts: high system density and aggressive testing
- New Jersey: densest contaminated water site concentration in the U.S.
Nationally, 8.0% of public water systems exceeded at least one EPA PFAS MCL. View PFAS data by state →
States with the Cleanest Water
States with consistently low violation rates and minimal PFAS detections include Hawaii, Vermont, New Hampshire, and Oregon. Common factors: newer infrastructure, smaller populations relative to system capacity, and aggressive state-level oversight that exceeds federal minimums.
Rural vs. Urban Water Quality
Water system size is the single biggest predictor of compliance. Systems serving more than 100,000 people have a violation rate of roughly 5%. Systems serving fewer than 500 people exceed 20%. Rural America disproportionately bears the burden of water quality problems.
What State Ranking Means for You
Living in a "high-ranked" state doesn't guarantee your individual system is safe, and living in a low-ranked state doesn't mean your water is contaminated. Always check your specific water system: Search your water system →