California’s large water systems have the cleanest legal compliance record in our data, but many still get low grades. Only 17 of the 176 California systems we grade (10%) had any EPA drinking water violation in the last three years, the lowest share of any state with at least 10 systems. Yet 91 of those 176 systems (52%) are graded D or F, and the average California score is 63 out of 100, below the national average of 68. The reason is that our grades also compare detected contaminants with health guidelines that are much stricter than legal limits. In California, PFAS, haloacetic acids and arsenic are the main reasons.
What this data covers
TapWaterSafety.org grades 1,000 public water systems that each serve more than 50,000 people. California has 176 of them, serving about 34.8 million people combined. The state has thousands more systems, mostly small ones. State Water Resources Control Board records counted 7,283 public water systems in California as of June 28, 2023, of which 2,851 were community water systems. Small systems are not in our data.
Source: EPA ECHO compliance records, checked October 7, 2026; last 12 quarters. Contaminant concerns come from the EWG-based contaminant data used for our grades.
Why a clean record can still mean a low grade
Under our methodology, legal compliance is only part of the score. The biggest piece (40%) compares detected contaminant levels with EWG’s health-based guidelines. Another 20% checks whether high-concern contaminants such as PFAS, arsenic or chromium-6 are detected at all. Grades run from A (85 to 100) down to F (below 55).
A California utility can meet every federal and state legal limit and still lose many points if it detects PFAS or haloacetic acids at levels above those health guidelines. That is the main pattern in this state. For more on the gap between health guidelines and legal limits, see EWG vs. EPA: the gap.
California grades at a glance
| Grade | California systems | People served |
|---|---|---|
| A | 3 | 0.45 million |
| B | 28 | 4.4 million |
| C | 54 | 14.9 million |
| D | 40 | 5.8 million |
| F | 51 | 9.2 million |
The three A-graded systems are the Helix Water District in La Mesa (89), the San Bernardino Valley WD (86) and the Beaumont Cherry Valley WD (85).
The ten largest California systems
| System | People served | Grade (score) | Any violation (last 12 quarters) |
|---|---|---|---|
| Los Angeles Dept. of Water & Power | 7,751,132 | C (70) | No |
| East Bay MUD | 1,442,800 | B (81) | No |
| City of San Diego | 1,385,379 | D (60) | No |
| San Jose Water | 1,039,920 | F (45) | Yes |
| SFPUC City Distribution Division | 848,019 | C (74) | No |
| Eastern Municipal WD | 666,581 | F (51) | No |
| City of Fresno | 545,716 | F (47) | No |
| City of Sacramento Main | 527,979 | F (48) | No |
| Long Beach Utilities | 466,772 | C (67) | No |
| Irvine Ranch Water District | 444,800 | F (47) | No |
Five of these ten are graded F, and four of those five have no violation at all in the last three years.
The most common concerns in California
Each system page lists its top three concerns. Across the 176 California systems:
- Haloacetic acids (HAA5) above EWG’s health guideline: 132 systems
- PFAS: 87 systems, serving about 14.9 million people, including 64 where PFHxS is listed above the health guideline
- Haloacetic acids (HAA9): 84 systems
- Arsenic: 76 systems
- Total trihalomethanes (TTHMs): 57 systems
- Chromium-6 (hexavalent chromium): 22 systems
- Nitrate: 3 systems
PFAS drives most F grades. Among the lowest-scoring California systems, nearly all list PFAS first, including the City of Monterey Park (F, 39), the City of Corona (F, 42) and the City of Manteca (F, 42). These are detections compared with health guidelines, not EPA violations. Under the 2024 federal PFAS rule, limits are not enforceable until 2029, and EPA has proposed pushing PFOA and PFOS compliance to 2031 (see EPA’s PFAS rule explained).
Haloacetic acids and TTHMs are disinfection byproducts. They form when chlorine or chloramine reacts with organic matter, and most California systems on our site use surface water. Our disinfection byproducts guide covers them.
Arsenic and chromium-6 occur naturally in many California groundwater sources. See our guides to arsenic and chromium-6.
California’s own standards
California often regulates ahead of the federal government. Three parts of its system matter for reading these results.
Public Health Goals (PHGs). The Office of Environmental Health Hazard Assessment (OEHHA) sets PHGs based only on health science, without considering cost. They are not enforceable. The State Water Board then sets enforceable limits (MCLs), which must be as close to the PHG as is technically and economically feasible, and never weaker than the federal limit. Our explainer on California’s public health goals goes deeper.
Chromium-6. California’s hexavalent chromium MCL of 10 micrograms per liter took effect October 1, 2024. Under the State Water Board’s schedule, systems with 10,000 or more service connections had until October 1, 2026 to comply. Smaller systems have until 2027 or 2028. EPA has no separate limit for chromium-6.
PFAS. California does not yet have its own enforceable PFAS limits. It uses notification levels (NLs) and response levels (RLs), which trigger public notice and recommended action. On October 29, 2025, the State Water Board updated the levels for PFOA, PFOS and PFHxS. The PFBS levels date from 2021.
| PFAS | Notification level | Response level |
|---|---|---|
| PFOA | 4.0 ppt | 10 ppt |
| PFOS | 4.0 ppt | 40 ppt |
| PFHxS | 3.0 ppt | 10 ppt |
| PFBS | 500 ppt | 5,000 ppt |
OEHHA adopted PHGs of 0.007 ppt for PFOA and 1 ppt for PFOS on April 5, 2024. The State Water Board lists PFAS standards among its priorities but has not set an adoption date.
The State Water Board took over the drinking water program from the California Department of Public Health on July 1, 2014, through its Division of Drinking Water.
EPA violations in California
| Measure | California systems | Share |
|---|---|---|
| At least one violation | 17 of 176 | 10% (9% of people served) |
| Health-based violation listed | 9 of 176 | 5% |
| EPA serious violator | 0 | 0% |
| Flagged over the lead action level | 1 | 1% |
| In violation all 12 quarters | 0 | 0% |
All 34 violation entries for California systems are listed as open in EPA’s record. Nine are health-based.
The 9 systems with a health-based violation
| System | People served | Grade | Health-based violation and start date |
|---|---|---|---|
| San Jose Water | 1,039,920 | F | Surface Water Treatment Rule (TT), June 2023 |
| City of Stockton | 191,302 | F | Disinfection byproducts (MCL), April 2023 |
| SCWA - Laguna/Vineyard | 184,896 | F | Lead and Copper Rule Revisions (TT), Oct. 17, 2024 |
| City of Fairfield | 120,377 | D | Lead and Copper Rule Revisions (TT), Oct. 17, 2024 |
| Cal-Am Water Coronado | 106,000 | F | Revised Total Coliform Rule (MCL), Aug. 2023 |
| City of Porterville | 63,487 | F | Lead and Copper Rule Revisions (TT), Oct. 17, 2024 |
| City of Monterey Park | 62,183 | F | Lead and Copper Rule Revisions (TT), Oct. 17, 2024 |
| City of Ceres | 54,513 | F | Lead and Copper Rule Revisions (TT), Oct. 17, 2024 |
| City of West Sacramento | 53,355 | D | Lead and Copper Rule Revisions (TT), Oct. 17, 2024 |
Six of the nine are Lead and Copper Rule Revisions treatment technique violations, each paired with a reporting violation and dated October 17, 2024. That is the day after the rule’s requirements, including the initial lead service line inventory, took effect. Our data does not show which requirement was missed, so check the EPA report or ask the utility. These entries are not lead test results.
The one system flagged over the lead action level is the City of Pleasanton, which has no violations listed. See water systems over the lead action level for what that flag means.
The rest of California’s violations are monitoring and reporting issues. The City of Corona had the most quarters in violation (11 of 12), all for monitoring violations across several chemical groups.
What California residents can do
- Look up your system on our search page or the California state page.
- Check your Consumer Confidence Report for PFAS, arsenic and chromium-6 results, and compare them with the state notification levels above.
- If PFAS is a concern, see our guide to filters for PFAS removal and confirm any model in the certifier’s online listing before buying.
- Compare with other states in our state rankings or with Texas.
Note: utilities may have resolved issues since October 7, 2026. Check each utility’s EPA ECHO report or its latest Consumer Confidence Report for current status.
Sources
- California State Water Resources Control Board: PFAS
- California State Water Resources Control Board: Hexavalent Chromium
- California State Water Resources Control Board: Hexavalent Chromium MCL FAQ
- California State Water Resources Control Board: The MCL Review Process
- OEHHA: Guide to Public Health Goals for Chemicals in Drinking Water
- California Senate: Drinking Water Program Transfer Report (July 2015)
- State Water Board: 2022–2023 report attachments to US EPA (public water system inventory)
- EPA ECHO: Detailed Facility Reports (linked from each utility page)