State Hub
California Water Quality
1,182
Utilities in database
36.4M
Residents served
102
With open violations
664
PFAS monitored
Quick Answer
California public drinking water is served by 1,182 EPA-tracked water systems, providing service to approximately 36.4 million residents through public utilities. 102 of those systems currently have open health-based violations on record in the EPA federal database. 664 systems have official PFAS monitoring records from the EPA UCMR 5 program (2023–2025). About 15% of CA residents use private wells, which fall outside federal utility compliance monitoring.
102 California water systems have open health-based violations recorded in EPA SDWIS. An open violation means a contaminant exceeded a federal limit and the violation has not been formally resolved in the federal database. Check individual utility pages for current status.
Open Health-Based Violations in California
Records sourced from EPA SDWIS. A record may be under review or resolved at the utility level but not yet updated in federal records. Water Utility Report does not determine whether water is safe to drink.
Drinking Water in California
California's drinking water comes from a complex mix of surface water (rivers, reservoirs) and groundwater. The state has some of the strictest water quality regulations in the U.S., but still faces challenges from agricultural runoff, legacy industrial contamination, and aging infrastructure in older cities. The State Water Resources Control Board maintains primacy for Safe Drinking Water Act enforcement.
Highest Risk Utilities
California systems with open health-based violations in EPA records.
Safest Large Utilities
California systems with no open health violations serving 10,000+ residents.
Utilities in California
251–275 of 1,182City of Hemet
CA3310016 · 33,828 served
Covina-city, Water Dept.
CA1910127 · 33,300 served
Camrosa Water District
CA5610063 · 32,700 served
Manhattan Beach-city, Water Dept.
CA1910083 · 32,697 served
Golden State Water Co - Barstow
CA3610043 · 32,547 served
East Niles Csd
CA1510006 · 32,517 served
Los Angeles Cwwd 29 & 80-malibu
CA1910204 · 32,348 served
City of Banning
CA3310006 · 31,680 served
City of Burlingame
CA4110003 · 31,451 served
La Verne, City Wd
CA1910062 · 31,334 served
City of Paso Robles Water Division
CA4010007 · 31,176 served
City of Santa Paula
CA5610011 · 31,018 served
City of Martinez
CA0710006 · 30,997 served
Scwa Mather-sunrise
CA3410704 · 30,825 served
Rincon Del Diablo Mwd (id-1)
CA3710018 · 30,757 served
Atascadero Mutual Water Co
CA4010002 · 30,618 served
Mid-peninsula Water District
CA4110001 · 30,609 served
Valley Center Mwd
CA3710026 · 29,938 served
Calif State Polytechnical Univ - Pomona
CA1910022 · 29,854 served
San Juan Water District
CA3410021 · 29,598 served
City of East Palo Alto
CA4110024 · 29,519 served
City of Atwater
CA2410001 · 29,479 served
Suisun-solano Water Authority
CA4810005 · 29,105 served
Vernon-city, Water Dept.
CA1910167 · 28,112 served
Placer Cwa - Auburn/bowman
CA3110005 · 27,294 served
Key Contaminant Concerns in California
These contaminants appear most frequently in California utility records or pose elevated risk in this region based on EPA data.
PFAS
Per- and polyfluoroalkyl substances (PFAS) are a class of over 12,000 synthetic chemicals characterized by strong carbon-fluorine bonds that resist degradation. The two most studied — PFOA (perfluorooctanoic acid) and PFOS (perfluorooctane sulfonic acid) — have been phased out of U.S. manufacturing but persist widely in the environment.
EPA limit: 4 ppt
Nitrates
Nitrate (NO₃⁻) is a nitrogen-containing compound that forms naturally through the decomposition of organic matter. At elevated concentrations — almost always caused by human activity — nitrate is converted in the digestive system to nitrite, which then reacts with hemoglobin to form methemoglobin, a form of hemoglobin that cannot carry oxygen. In the body, nitrite also reacts with amines in food to form N-nitroso compounds (nitrosamines) — known carcinogens classified by the IARC as Group 2A (probable human carcinogens). The United States applies over 23 million tons of nitrogen fertilizer annually, making agricultural runoff the dominant source of nitrate contamination in U.S. groundwater.
EPA limit: 10 mg/L
DBPs
When utilities add chlorine to water to kill pathogens, it reacts with dissolved organic matter — leaves, algae, soil — to produce disinfection byproducts (DBPs). Over 600 DBPs have been identified. The EPA regulates two groups: total trihalomethanes (TTHMs, including chloroform) and haloacetic acids (HAA5). DBP levels tend to be highest in surface water systems and in warm months when organic matter is elevated.
EPA limit: 80 µg/L (TTHMs) / 60 µg/L (HAA5)
Arsenic
Arsenic (As) occurs naturally in rock and soil, dissolving into groundwater through natural weathering processes. Inorganic arsenic — the form found in drinking water — is a known human carcinogen. The western United States has particularly arsenic-rich geological formations, but elevated levels have been found in 48 states. Arsenic is tasteless and odorless.
EPA limit: 10 ppb
City Water Reports in California
Tap water quality pages for California cities — violations, PFAS records, utility profiles, and official source links.
Independent Water Testing
Find a certified lab in California
Utility compliance records show what water systems report to the EPA. An independent test from a certified laboratory confirms what's actually in your tap water. California labs can test for PFAS, lead, nitrates, bacteria, and dozens of other contaminants.
Explore Water Quality in California
City of Hemet
Violation history, PFAS records, and official source links
Covina-city, Water Dept.
Violation history, PFAS records, and official source links
Camrosa Water District
Violation history, PFAS records, and official source links
PFAS monitoring records — California
664 water systems in California with EPA UCMR 5 records
Active drinking water violations
102 open health-based violations on record — view official EPA SDWIS data
Lead in California drinking water
State-specific lead data, violation utilities, and testing guidance
PFAS in California drinking water
State-specific PFAS data, MCL context, and treatment options
Certified water testing labs in California
Labs certified for PFAS (EPA 533/537.1), lead, and bacteria testing
Water treatment options
Reverse osmosis, activated carbon, and filtration guides with cost ranges
Data sources and methodology
How WaterUtilityReport.com sources and validates official EPA data
Common Questions About California Drinking Water
Does California drinking water have PFAS?
664 California water systems have EPA UCMR 5 PFAS monitoring records (2023–2025)
Which California water utilities have open violations?
102 systems have open health-based violations in EPA SDWIS — search for your utility
How do I test my water in California?
State-certified labs for PFAS (EPA 533/537.1), lead, nitrate, and bacteria testing
What treatment removes PFAS from CA tap water?
Reverse osmosis removes PFAS, lead, arsenic, and nitrates — cost, maintenance, and NSF certification explained
What do California PFAS records tell me about my water?
EPA limits, health context, and what UCMR 5 detection above MRL means for your water
How is California water quality data sourced here?
EPA SDWIS violations, UCMR 5 PFAS records, and CCR data — sources, accuracy notes, and limitations
California Water FAQs
Data sources: Utility compliance and violation data from EPA SDWIS (Safe Drinking Water Information System). PFAS monitoring records from EPA UCMR 5 (Unregulated Contaminant Monitoring Rule 5, 2023–2025). Contaminant data from EPA and ATSDR public references. This page summarizes public records — it is not a compliance determination. Methodology →
Last updated: 2025-01-10