CheckPFAS

By compound · EPA limit 4 ppt

Where PFOS contamination is worst

Perfluorooctane sulfonic acid — 1,309 U.S. public water systems measured PFOS above the EPA's 4 ppt limit during 2023–2025 UCMR 5 testing. They're ranked below by how far over the limit they tested.

EPA limit (MCL)
4 ppt
Systems above the limit
1,309
Worst result
490.0 ppt (123×) — NASHVILLE, TOWN OF, NC

Systems exceeding the PFOS limit

100 of 1,309
# Water system State PFOS measured × limit
1 NASHVILLE, TOWN OF NC 490.0 ppt 123×
2 RUNNING SPRINGS WATER DISTRICT CA 236.5 ppt 59×
3 ARTONDALE WATER SYSTEM WA 153.6 ppt 38×
4 EMMAUS BOROUGH PUBLIC WATER PA 153.0 ppt 38×
5 GWA NORTHERN WATER SYSTEM GU 135.0 ppt 34×
6 NEW MARTINSVILLE WV 121.8 ppt 30×
7 YESHIVA FARM SETTLEMENT NY 106.0 ppt 27×
8 CITY OF GRAND PRAIRIE TX 82.0 ppt 21×
9 ORANGEWOOD WATER SYSTEM FL 80.8 ppt 20×
10 CITY OF OXFORD MS 72.2 ppt 18×
11 POTRERO ELEMENTARY SCHOOL CA 64.2 ppt 16×
12 IRONDALE WATER SYSTEM AL 59.4 ppt 15×
13 LIBERTY UTILITIES - BELLFLOWER-NORWALK CA 59.0 ppt 15×
14 AUDUBON WATER COMPANY PA 57.9 ppt 14×
15 LAFAYETTE GA 56.0 ppt 14×
16 TEMPE CITY OF AZ 55.8 ppt 14×
17 SOMERS TOWN HOUSE/HALL NY 54.7 ppt 14×
18 MONTEBELLO LAND & WATER CO. CA 53.0 ppt 13×
19 LAKE PANASOFFKEE WATER ASSN 2WPS FL 53.0 ppt 13×
20 MOSES LAKE CITY OF WA 52.2 ppt 13×
21 BROKEN ARROW MUNICIPAL AUTHORITY OK 51.3 ppt 13×
22 AUGUSTA-RICHMOND CO WS GA 51.0 ppt 13×
23 DARTMOUTH WATER DIVISION MA 50.6 ppt 13×
24 FKAA J. ROBERT DEAN W.T.P. FL 50.3 ppt 13×
25 TOWN OF THURMONT MD 48.0 ppt 12×
26 HARRISON CO WATER ASSOC KY 47.9 ppt 12×
27 AIBONITO LA PLATA PR 46.7 ppt 12×
28 BARROW UTILITIES & ELEC. COOP., INC. (BU AK 46.3 ppt 12×
29 ELKO CITY OF NV 46.0 ppt 12×
30 CITY OF ATWATER CA 45.0 ppt 11×
31 NORTH MIAMI, CITY OF FL 45.0 ppt 11×
32 DOWNEY - CITY, WATER DEPT. CA 44.0 ppt 11×
33 NORTH BAY VILLAGE, CITY OF FL 43.3 ppt 11×
34 PAYSON TOWN OF AZ 42.2 ppt 11×
35 BAL HARBOUR VILLAGE FL 42.0 ppt 11×
36 CITY OF SACRAMENTO MAIN CA 41.4 ppt 10×
37 CITY OF CLOVIS CA 41.0 ppt 10×
38 LIBERTY WATER RIO RICO AZ 40.9 ppt 10×
39 PALMERTON MUNICIPAL AUTHORITY PA 40.0 ppt 10×
40 OCALA, CITY OF (2 WTPS) FL 39.0 ppt 9.8×
41 PALM SPRINGS, VILLAGE OF FL 39.0 ppt 9.8×
42 BEAR TAVERN SCHOOL NJ 38.1 ppt 9.5×
43 MDWASA/REX UTILITIES FL 37.4 ppt 9.3×
44 NATICK WATER DEPARTMENT MA 37.3 ppt 9.3×
45 LAUDERHILL, CITY OF FL 37.0 ppt 9.3×
46 CYNTHIANA MUNICIPAL WATER WORKS KY 37.0 ppt 9.3×
47 TARPON SPRINGS WATER SYSTEM FL 36.9 ppt 9.2×
48 TRACT 349 MUTUAL WATER CO. CA 36.5 ppt 9.1×
49 EMERALD COAST UTILITIES AUTHORITY FL 35.7 ppt 8.9×
50 LANTANA WATER TREATMENT PLANT FL 35.7 ppt 8.9×
51 GREENSBORO, CITY OF NC 35.6 ppt 8.9×
52 DUXBURY WATER DEPARTMENT MA 35.0 ppt 8.8×
53 PEMBROKE PINES, CITY OF FL 34.7 ppt 8.7×
54 WAGONER CO. RWD #5 OK 34.0 ppt 8.5×
55 HORSHAM WATER&SEWER AUTHORITY PA 33.8 ppt 8.4×
56 BROOKWOOD COMM WTR SYSTEM NC 33.3 ppt 8.3×
57 TOWN OF ANTHONY TX 33.1 ppt 8.3×
58 ATASCADERO STATE HOSPITAL CA 33.0 ppt 8.3×
59 MDWASA - MAIN SYSTEM FL 33.0 ppt 8.3×
60 WINNSBORO TOWN OF (2010001) SC 32.8 ppt 8.2×
61 BELLFLOWER MUNICIPAL WATER SYSTEM CA 32.6 ppt 8.2×
62 GADSDEN WATER WORKS AND SEWER BOARD AL 32.4 ppt 8.1×
63 LADY LAKE CENTRAL - WPS 1,2,3 FL 32.4 ppt 8.1×
64 HAWLEY WSC TX 32.3 ppt 8.1×
65 Commonwealth Utilities Corp (Saipan) MP 32.1 ppt 8.0×
66 ALOHA GARDENS UTILITIES FL 31.8 ppt 8.0×
67 NORCO, CITY OF CA 31.4 ppt 7.8×
68 BEALETON REGIONAL VA 31.1 ppt 7.8×
69 STERRETT-VANDIVER WATER SYSTEM AL 31.0 ppt 7.8×
70 PEOPLES WATER SERVICE COMPANY FL 31.0 ppt 7.8×
71 RIVIERA BEACH UTILITY DISTRICT, CITY OF FL 31.0 ppt 7.8×
72 SAUKVILLE WATERWORKS WI 31.0 ppt 7.8×
73 MOORE CREEK MOUNT CARMEL UTILITIES FL 30.2 ppt 7.5×
74 CITY OF FRESNO CA 30.0 ppt 7.5×
75 PICO RIVERA - CITY, WATER DEPT. CA 30.0 ppt 7.5×
76 CITY OF ABILENE TX 30.0 ppt 7.5×
77 COLBERT COUNTY RURAL WATER SYSTEM AL 29.5 ppt 7.4×
78 WAGONER CO. RWD #4 OK 29.5 ppt 7.4×
79 WETUMPKA WATER WORKS & SEWER BOARD AL 29.0 ppt 7.3×
80 CITY OF ANAHEIM CA 29.0 ppt 7.3×
81 NORTH LAUDERDALE, CITY OF FL 29.0 ppt 7.3×
82 CALHOUN GA 29.0 ppt 7.3×
83 KINGS ISLAND PWS OH 28.9 ppt 7.2×
84 DELRAY BEACH PUBLIC WATER SYSTEM FL 28.7 ppt 7.2×
85 BCWWS 2A FL 28.4 ppt 7.1×
86 GARDEN CITY WATER AND SEWER SYSTEM ID 28.2 ppt 7.0×
87 CLANTON WATER DEPARTMENT AL 28.0 ppt 7.0×
88 PICO WD CA 28.0 ppt 7.0×
89 HIGHLAND WATER AUTHORITY AL 27.8 ppt 7.0×
90 SHELBY COUNTY WATER SYSTEM AL 27.7 ppt 6.9×
91 CITY OF MARGATE FL 27.7 ppt 6.9×
92 HIALEAH, CITY OF FL 27.6 ppt 6.9×
93 FORT CAMPBELL WATER SYSTEM TN 27.3 ppt 6.8×
94 BCWWS 3A FL 27.2 ppt 6.8×
95 HALLANDALE BEACH, CITY OF FL 27.0 ppt 6.8×
96 COCONUT CREEK, CITY OF FL 27.0 ppt 6.8×
97 TRENTON WATER SYSTEM TN 27.0 ppt 6.8×
98 GRAND BAY WATER WORKS BOARD AL 26.9 ppt 6.7×
99 MAYWOOD MUTUAL WATER CO. #3 CA 26.4 ppt 6.6×
100 CITY OF BOERNE TX 26.3 ppt 6.6×

Showing the 100 most severe of 1,309 systems exceeding the PFOS limit.

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 PFOS at the tap. Source: EPA UCMR 5 (2023–2025). Methodology.