PFAS · California
PFAS in California drinking water: EPA’s final survey results
EPA’s national PFAS survey (UCMR 5) tested 691 of the community water systems that serve homes in California. 236 found at least one of 29 PFAS above the laboratory reporting level, and 128 had a PFOA or PFOS sampling-location yearly average at or above EPA’s 4.0 ppt limit. Samples were collected from January 2023 to June 2026.
Data as of EPA UCMR 5 final release, August 2026 (file dated Aug 28, 2026) · EPA SDWIS 2026Q2 (file dated Jul 9, 2026). How we build these pages
PFHxS was the compound California community systems found most often: 147 of 689 tested systems measured it above the reporting level. Across the country, 35% of surveyed community systems found at least one PFAS; in California the share is 34%. The largest California system with a detection, East Bay MUD, serves 1,442,800 people and found 2 of the 29 compounds.
Which PFAS were found most often in California
Each row counts the California community water systems where that compound was measured above the reporting level at least once. A detection is a measurement, not a violation: most of these compounds have no federal limit.
| Compound | Systems where found | Systems tested | Share |
|---|---|---|---|
| PFHxS | 147 | 689 | 21% |
| PFOS | 146 | 689 | 21% |
| PFPeA | 141 | 689 | 20% |
| PFHxA | 131 | 689 | 19% |
| PFOA | 122 | 689 | 18% |
| PFBS | 108 | 689 | 16% |
| PFBA | 84 | 689 | 12% |
| PFHpA | 52 | 689 | 8% |
| PFNA | 7 | 689 | 1% |
| PFPeS | 7 | 689 | 1% |
| 6:2 FTS | 5 | 689 | 1% |
| PFDA | 5 | 689 | 1% |
California systems with the most PFAS found
The 10 surveyed community water systems that found the most different PFAS, with PFOA and PFOS compared to EPA’s 4.0 ppt limits on the yearly average at the highest sampling location. Larger systems come first when counts tie.
| Water system | People served | PFAS found (of 29) | PFOA | PFOS |
|---|---|---|---|---|
| City of Fresno CA1010007 | 545,716 | 10 | 13.5 ppt at or above the MCL | 21.5 ppt at or above the MCL |
| City of Clovis CA1010003 | 130,130 | 10 | 16.0 ppt at or above the MCL | 36.0 ppt at or above the MCL |
| City of Atwater CA2410001 | 29,479 | 10 | 16.5 ppt at or above the MCL | 22.5 ppt at or above the MCL |
| Running Springs Water District CA3610062 | 5,268 | 10 | 11.7 ppt at or above the MCL | 131 ppt at or above the MCL |
| Pico Rivera - City, Water Dept. CA1910042 | 40,600 | 9 | 12.6 ppt at or above the MCL | 28.5 ppt at or above the MCL |
| Pico WD CA1910125 | 22,051 | 9 | 12.5 ppt at or above the MCL | 25.5 ppt at or above the MCL |
| Riverside Highland Water Company CA3610057 | 20,188 | 9 | 16.5 ppt at or above the MCL | 15.5 ppt at or above the MCL |
| Ukiah, City of CA2310003 | 16,607 | 9 | 1.7 ppt below the MCL | 4.1 ppt at or above the MCL |
| City of Sacramento Main CA3410020 | 527,979 | 8 | 16.5 ppt at or above the MCL | 38.8 ppt at or above the MCL |
| Santa Clarita Valley Water Agency CA1910240 | 294,090 | 8 | 14.0 ppt at or above the MCL | 6.9 ppt at or above the MCL |
Counties with the most systems that found PFAS
- Los Angeles County 64 of 118 surveyed systems
- San Bernardino County 24 of 49 surveyed systems
- Orange County 18 of 30 surveyed systems
- Sacramento County 15 of 29 surveyed systems
- Riverside County 13 of 31 surveyed systems
- San Diego County 9 of 27 surveyed systems
- San Luis Obispo County 8 of 17 surveyed systems
- Fresno County 7 of 21 surveyed systems