10 water systems with the highest PFAS contamination
The EPA finalized enforceable PFAS limits in April 2024 — 4 ppt for PFOA and PFOS (others vary). These are the 10 water systems where regulated PFAS were found at the highest levels above those MCLs in EPA UCMR5 national monitoring. Each card lists every regulated compound over the limit with measured ppt and how many times above the limit. The worst single compound here is about 123× over its MCL.
PFAS contamination in drinking water is heavily concentrated around military installations. The US military used AFFF (Aqueous Film-Forming Foam) — a highly effective but PFAS-laden firefighting agent — at bases and air stations for decades. During training exercises and emergency responses, AFFF was discharged directly onto tarmacs and into soil, where PFAS leached into groundwater and nearby water supplies. Hundreds of military installations have known PFAS contamination in their surrounding communities.
The EPA set the PFOA/PFOS MCL at 4 ppt — itself a level that reflects what's technically achievable, not a perfectly "safe" threshold. At 490 ppt, the Cape Fear system is delivering PFOS at concentrations 122 times that limit. Long-term exposure at these levels is associated with significantly elevated cancer risk, immune suppression, and hormonal disruption. Drinking water is not the only PFAS exposure route, but it is one of the most direct and controllable ones.
Reverse osmosis (RO) systems certified to NSF/ANSI 58 remove 99%+ of PFAS including PFOA, PFOS, and GenX. Granular activated carbon (GAC) used in whole-house systems can remove 60–90% of some PFAS at adequate contact time. Standard pitcher filters (including most Brita products) are not certified for PFAS removal and should not be relied on in contaminated areas. For drinking and cooking water, an under-sink or countertop RO is the gold standard.
Enter your ZIP code above to see the UCMR5 PFAS data, violation history, and contaminant profile for your specific water utility.
Enter your ZIP to see the UCMR5 PFAS readings, MCL violations, and certified filter recommendations for your specific water system.
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