By compound · EPA limit 10 ppt
Where PFNA contamination is worst
Perfluorononanoic acid — 21 U.S. public water systems measured PFNA above the EPA's 10 ppt limit during 2023–2025 UCMR 5 testing. They're ranked below by how far over the limit they tested.
EPA limit (MCL)
10 ppt Systems above the limit
21 Worst result
99.8 ppt (10.0×) — EMMAUS BOROUGH PUBLIC WATER, PA Systems exceeding the PFNA limit
21 of 21| # | Water system | State | PFNA measured | × limit |
|---|---|---|---|---|
| 1 | EMMAUS BOROUGH PUBLIC WATER | PA | 99.8 ppt | 10.0× |
| 2 | EAST GREENWICH TWP WATER DEPT | NJ | 73.3 ppt | 7.3× |
| 3 | CAPITOL WATER CORP | ID | 51.0 ppt | 5.1× |
| 4 | LOCUST VALLEY WD | NY | 29.6 ppt | 3.0× |
| 5 | PEQUENAKONCK ELEMENTARY SCHOOL | NY | 26.4 ppt | 2.6× |
| 6 | CITY OF PFLUGERVILLE | TX | 25.2 ppt | 2.5× |
| 7 | MANVILLE WSC | TX | 24.3 ppt | 2.4× |
| 8 | QUAKERTOWN BORO | PA | 24.0 ppt | 2.4× |
| 9 | PALMERTON MUNICIPAL AUTHORITY | PA | 21.1 ppt | 2.1× |
| 10 | GEORGETOWN WATER DEPARTMENT | DE | 20.0 ppt | 2.0× |
| 11 | MANHASSET LAKEVILLE WD | NY | 19.0 ppt | 1.9× |
| 12 | WESTVILLE WATER DEPARTMENT | NJ | 16.7 ppt | 1.7× |
| 13 | EMERALD COAST UTILITIES AUTHORITY | FL | 16.2 ppt | 1.6× |
| 14 | HO HO KUS WATER DEPT | NJ | 16.1 ppt | 1.6× |
| 15 | WEST DEPTFORD TWP WATER DEPT | NJ | 16.0 ppt | 1.6× |
| 16 | BROOKLAWN WATER DEPARTMENT | NJ | 15.3 ppt | 1.5× |
| 17 | AMBLER BORO WATER DEPT | PA | 13.5 ppt | 1.4× |
| 18 | FALLSBURG WHO-LS-SF | NY | 12.3 ppt | 1.2× |
| 19 | AQUA PA MAIN SYSTEM | PA | 12.0 ppt | 1.2× |
| 20 | SUEZ WATER DELAWARE | DE | 11.6 ppt | 1.2× |
| 21 | POTRERO ELEMENTARY SCHOOL | CA | 10.2 ppt | 1.0× |
Being above the limit means the utility must reduce levels to comply by 2029 — not that the water is acutely unsafe today. A certified NSF/ANSI 53 or 58 filter reduces PFNA at the tap. Source: EPA UCMR 5 (2023–2025). Methodology.