707 public water systems in California were sampled in EPA's UCMR 5 programme (2023–2025); we show six PFAS and lithium. Read 2026-10-31.
166 of 707 systems had at least one sample above a 2024 federal limit; 445 had at least one PFAS found above the reporting level; 262 had none found above the reporting level.
A single sample above a 2024 limit is a measurement, not a violation. Compliance is judged on running yearly averages, and water systems have until 2029 to meet the limits. On 20 May 2026 EPA proposed giving qualifying systems until 2031 for PFOA and PFOS and removing the limits for PFHxS, PFNA and HFPO-DA; those proposals were not final when we last checked (5 Nov 2026). Counts are per system, not per person; population figures are available only for systems serving more than 25,000 people (about 35,312,226 people across those systems here). UCMR 5 was a one-time national monitoring programme (2023–2025). The results are a snapshot at the system's entry points or taps on the sample dates, not a continuous measurement and not a compliance record.
| System | People served | UCMR 5 result |
|---|---|---|
| Los Angeles Los Angeles-City, Dept. of Water & Power | 3,875,566 | None detected (below the reporting level) |
| East Bay MUD (EBMUD) East Bay Mud | 1,468,000 | None detected (below the reporting level) |
| San Diego San Diego, City of | 1,408,937 | None detected (below the reporting level) |
| San Jose San Jose Water | 1,039,920 | Above the 2024 limit in at least one sample |
| San Francisco PUC city distribution Sfpuc City Distribution Division | 848,019 | None detected (below the reporting level) |
| Eastern Municipal Water District Eastern Municipal Wd | 659,923 | None detected (below the reporting level) |
| Fresno City of Fresno | 545,970 | Above the 2024 limit in at least one sample |
| Sacramento City of Sacramento Main | 527,979 | Above the 2024 limit in at least one sample |
| Long Beach Long Beach-City, Water Dept. | 466,772 | None detected (below the reporting level) |
| Irvine Irvine Ranch Water District | 450,323 | None detected (below the reporting level) |
| Anaheim City of Anaheim | 350,254 | Above the 2024 limit in at least one sample |
Pages for these are being added in stages. The data for all 707 systems is in the public dataset.
| System | People served | UCMR 5 result |
|---|---|---|
| Alameda County Water District Alameda County Water District | 344,000 | None detected (below the reporting level) |
| City of Santa Ana City of Santa Ana | 316,184 | Above the 2024 limit in at least one sample |
| Riverside, City of Riverside, City of | 302,776 | Detected, below the 2024 limit |
| Santa Clarita Valley W.A.-Valencia Divis Santa Clarita Valley W.A.-Valencia Divis | 292,014 | Above the 2024 limit in at least one sample |
| Helix Water District Helix Water District | 277,918 | None detected (below the reporting level) |
| Gswc - Southwest Gswc - Southwest | 277,740 | None detected (below the reporting level) |
| Coachella Vwd: Cove Community Coachella Vwd: Cove Community | 270,000 | None detected (below the reporting level) |
| Cws - Bakersfield Cws - Bakersfield | 268,129 | Above the 2024 limit in at least one sample |
| Otay Water District Otay Water District | 242,155 | None detected (below the reporting level) |
| San Gabriel Valley Water Co.-El Monte San Gabriel Valley Water Co.-El Monte | 240,000 | None detected (below the reporting level) |
| San Gabriel Valley Wc - Fontana San Gabriel Valley Wc - Fontana | 228,270 | None detected (below the reporting level) |
| Modesto, City of Modesto, City of | 218,915 | Above the 2024 limit in at least one sample |
| San Bernardino City San Bernardino City | 214,665 | Detected, below the 2024 limit |
| Cucamonga Valley Water District Cucamonga Valley Water District | 213,375 | None detected (below the reporting level) |
| Contra Costa Water District Contra Costa Water District | 210,500 | None detected (below the reporting level) |
| Los Angeles Cwwd 40,Reg 4 & 34-Lancaster Los Angeles Cwwd 40,Reg 4 & 34-Lancaster | 208,129 | None detected (below the reporting level) |
| City of Huntington Beach City of Huntington Beach | 201,000 | Above the 2024 limit in at least one sample |
| Oxnard Water Dept Oxnard Water Dept | 200,232 | None detected (below the reporting level) |
| Sacramento Suburban Water District Sacramento Suburban Water District | 194,444 | Detected, below the 2024 limit |
| City of Stockton City of Stockton | 192,702 | Above the 2024 limit in at least one sample |
| Glendale-City, Water Dept. Glendale-City, Water Dept. | 192,212 | Above the 2024 limit in at least one sample |
| Scwa - Laguna/Vineyard Scwa - Laguna/Vineyard | 188,417 | Above the 2024 limit in at least one sample |
| Marin Municipal Water District Marin Municipal Water District | 188,116 | None detected (below the reporting level) |
| Ontario Municipal Utilities Company Ontario Municipal Utilities Company | 185,010 | Above the 2024 limit in at least one sample |
| Sweetwater Authority Sweetwater Authority | 184,915 | Above the 2024 limit in at least one sample |