National PFAS Contamination Heatmap
Every US county tested by EPA UCMR 5 (2023–2025), colored by its maximum detected PFAS concentration. Click any county to see detailed testing results and the ZIP codes in that county. Tip: click a county to pin its details and follow through to state-level data.
Each county is colored by its maximum detected PFAS concentration across all tested water systems. Data is from EPA's fifth Unregulated Contaminant Monitoring Rule (UCMR 5), which tested ~10,000 public water systems for 29 PFAS compounds from 2023 through 2025. About 98% of all PFAS tests come back below the detection limit, so a "Not detected" reading in the tooltip means the system's samples were genuinely clean under UCMR 5 methodology — not that data is missing.
Counties shown in red or dark red have systems exceeding EPA's 4 ppt Maximum Contaminant Level for PFOA/PFOS. Green counties were tested and nothing was detected. Dark counties have no UCMR 5 data yet — typically smaller systems EPA did not sample.
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The map shows county-level aggregates. For your specific water utility and household-level detail, look up your ZIP code directly.
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