PFAS detected in California water systems

EPA UCMR 5 monitoring (2023–2025) detected PFOA or PFOS at or above 6 parts per trillion in these 91 large California public water systems, each serving more than 10,000 people. Select a system to see exactly what was detected and the certified filters that reduce it.

California systems, highest detections first

Water system PFOA (ppt) PFOS (ppt) vs. 4 ppt reference
Liberty Utilities - Bellflower-Norwalk 16 59 14.8×
Montebello Land & Water Co. 16 53 13.3×
City of Atwater 33 45 11.3×
Downey - City, Water Dept. 15 44 11×
City of Sacramento Main 17.3 41.4 10.3×
City of Clovis 18 41 10.3×
Norco, City of 13.7 31.4 7.8×
City of Fresno 16 30 7.5×
Ontario Municipal Utilities Company 30 5.2 7.5×
Pico Rivera - City, Water Dept. 16 30 7.5×
City of Anaheim 10.1 29 7.3×
Pico WD 14 28 7×
City of Pleasanton 5.1 26 6.5×
Modesto, City of 8.6 26 6.5×
Norwalk - City, Water Dept. 5.2 26 6.5×
South Gate-City, Water Dept. 10 26 6.5×
Ceres, City of 12 24 6×
SCWA - Laguna/Vineyard 14 24 6×
Tract 180 Mutual Water Co. 6.5 24 6×
City of Bell Gardens 14 23 5.8×
Huntington Park-City, Water Dept. 5.1 23 5.8×
Lynwood-City, Water Dept. 7.8 23 5.8×
Orchard Dale Water District 9.9 23 5.8×
Porterville, City of 22 23 5.8×
Cal-Water Service Co.-Chico 6.8 22.5 5.6×
Atascadero Mutual Water Co 8.4 22.3 5.6×
GSWC-South Arcadia 5.5 22 5.5×
Santa Clarita Valley W.A.-Santa Clarita 20.5 17.8 5.1×
City of Garden Grove 8.1 19 4.8×
Riverside Highland Water Company 18 19 4.8×
Colton, City of 5.9 18 4.5×
Pomona - City, Water Dept. 7.1 18 4.5×
Bellflower - Somerset MWC — 17 4.3×
Camrosa Water District — 17 4.3×
City of Lathrop — 17 4.3×
City of Orange 9.3 17 4.3×
Compton-City, Water Dept. 4.9 17 4.3×
Liberty Utilities - Lynwood 5 17 4.3×
Santa Clarita Valley W.A.-Valencia Divis 16.9 7.5 4.2×
Lakewood - City, Water Dept. — 16.7 4.2×
City of Redding 16.2 12.6 4×
Golden State WC - West Orange County 8.1 16 4×
Rancho California Water District 11 16 4×
Suburban Water Systems-La Mirada 7 16 4×
Glendale-City, Water Dept. 14.8 15.8 4×
GSWC - Bell, Bell Gardens — 15 3.8×
Calam - Parkway 4.3 14.7 3.7×
City of Santa Ana 8.9 14.2 3.5×
CWS - Bakersfield 9.1 14 3.5×
Santa Fe Springs - City, Water Dept. 6.9 14 3.5×
Cal Am - Suburban Rosemont 8.2 13.4 3.4×
City of Fullerton 10.8 13.3 3.3×
GSWC - Artesia — 13 3.3×
Suburban Water Systems - Whittier 6.3 13 3.3×
GSWC - Claremont 12.9 10.4 3.2×
California State University Fresno 12 — 3×
California Water Service - Livermore 4.8 12 3×
East Valley Water District 9 12 3×
Pinedale County Water District 12 8.8 3×
Ripon, City of 5.2 12 3×
Sweetwater Authority 11.4 5.7 2.9×
Hesperia WD 10.2 11.1 2.8×
Lindsay, City of 8.3 11 2.8×
City of Arcadia — 10 2.5×
City of Vacaville 5.1 10 2.5×
Big Bear City CSD 4.5 9.9 2.5×
City of Merced 6.1 8.9 2.2×
California Water Service Co. - Ela — 8.6 2.1×
Cal Am Water Company - Monterey 8.1 7.3 2×
City of Gilroy 8 5.8 2×
Azusa Light and Water 7.7 5.8 1.9×
Bakersfield, City of — 7.6 1.9×
City of Red Bluff 7.4 — 1.9×
Ukiah, City of 6.9 7.4 1.9×
Rialto, City of 7.3 — 1.8×
Manteca, City of 7 — 1.8×
CWS - Visalia 4.2 6.9 1.7×
Arroyo Grande, Water Department 5.8 6.8 1.7×
City of Buena Park — 6.8 1.7×
City of Sanger 5.6 6.7 1.7×
Golden State WC - Placentia/Yorba Linda 6 6.5 1.6×
Watsonville, City of 6.5 5.1 1.6×
Paso Robles Water Department 6.3 — 1.6×
Lodi, City of 6.2 5.6 1.6×
San Jose Water — 6.2 1.6×
Sonoma, City of 6.2 — 1.6×
Big Bear Lake DWP - Big Bear System 5.5 6.1 1.5×
City of Huntington Beach — 6.1 1.5×
Monrovia-City, Water Dept. 5.4 6.1 1.5×
South Tahoe PUD - Main 6.1 5.2 1.5×
SCWA - Arden Park Vista — 6 1.5×

Highest single EPA UCMR 5 detections (2023–2025), in parts per trillion. The last column is the multiple of the 4 ppt federal reference level for PFOA/PFOS — shown as context only, not a compliance or health determination. — means the compound was not detected at or above 6 ppt.

Not sure what's in your own water? Test it first, then run the selector for a recommendation matched to your home, or read what PFAS is and how it's removed.