California drinking water quality
California has 7,384 active public water systems serving 42.1 million people. 2,487 of them, 34%, had at least one EPA violation in the past three years, 1,207 have an unresolved violation today, and 43 are designated serious violators by the EPA.
Active systems
7,384
in 58 counties
People served
42.1M
2,920 community systems serve 40M
Violations, past 3 years
2,487
34% of active systems
Serious violators
43
798 systems carry a health flag
Largest counties
All 58 counties| County | People served | Systems | With violations |
|---|---|---|---|
| Los Angeles | 10,081,756 | 271 | 66 |
| San Diego | 3,535,829 | 198 | 83 |
| Orange | 3,204,616 | 46 | 6 |
| Riverside | 2,719,341 | 198 | 66 |
| San Bernardino | 2,573,235 | 321 | 146 |
| Alameda | 2,273,899 | 27 | 4 |
| Santa Clara | 2,074,486 | 119 | 41 |
| Sacramento | 1,657,158 | 164 | 69 |
| Kern | 1,062,083 | 336 | 82 |
| Fresno | 1,005,373 | 339 | 128 |
Largest community water systems
All 7,384 systems| System | Serves | Status |
|---|---|---|
| Los Angeles-City, Dept. of Water & Power Los Angeles County |
3,875,566 | |
| East Bay MUD Alameda County |
1,468,000 | |
| San Diego, City of San Diego County |
1,408,937 | |
| San Jose Water Santa Clara County |
1,039,920 | |
| Sfpuc City Distribution Division San Francisco County |
848,019 | |
| Eastern Municipal WD Riverside County |
659,923 | |
| City of Fresno Fresno County |
545,970 | |
| City of Sacramento Main Sacramento County |
527,979 | |
| Long Beach Utilities Department Los Angeles County |
466,772 | |
| Irvine Ranch Water District Orange County |
450,323 |
About the California data
Retrieved from EPA ECHO on Oct 11, 2026. EPA records for California systems do not include town names, so searches here match on ZIP code, street address, or county.