All water systems in California
7,380 systems
| System | Serves | Status | Rules violated, 3 yr | Unresolved |
|---|---|---|---|---|
|
Cwsc los Altos Suburban Santa Clara County |
63,559 | 0 | 0 | |
|
Porterville, City of Porterville · Tulare County |
63,487 | 1 | 1 | |
|
Gswc Florence/graham Los Angeles County |
63,472 | 0 | 0 | |
|
Liberty Utilities (av Ranchos) Corp. San Bernardino County |
63,381 | 0 | 0 | |
|
California Water Service-S San Francisco San Mateo County |
62,609 | 0 | 0 | |
|
City of Pittsburg Pittsburg · Contra Costa County |
62,500 | 0 | 0 | |
|
Hanford, City of Hanford · Kings County |
62,127 | 1 | 0 | |
|
North Marin Water District Marin County |
61,691 | 0 | 0 | |
|
City of Woodland Woodland · Yolo County |
61,462 | 0 | 0 | |
|
Petaluma, City of Petaluma · Sonoma County |
61,427 | 0 | 0 | |
|
City of la Habra La Habra · Orange County |
61,202 | 0 | 0 | |
|
Monterey Park-City, Water Dept. Monterey Park · Los Angeles County |
61,096 | 1 | 1 | |
|
California Water Service Livermore Alameda County |
60,414 | 0 | 0 | |
|
California Water Service Bear Gulch San Mateo County |
60,382 | 0 | 0 | |
|
City of Gilroy Gilroy · Santa Clara County |
59,426 | 0 | 0 | |
|
Rialto, City of Rialto · San Bernardino County |
59,264 | 0 | 0 | |
|
Suburban Water Systems-La Mirada Los Angeles County |
57,240 | 0 | 0 | |
|
City of Fountain Valley Fountain Valley · Orange County |
56,747 | 0 | 0 | |
|
Gswc-San Dimas Los Angeles County |
56,564 | 0 | 0 | |
|
Monte Vista WD San Bernardino County |
56,390 | 0 | 0 | |
|
City of Lincoln Lincoln · Placer County |
56,268 | 0 | 0 | |
|
Alco Water Service Monterey County |
56,253 | 0 | 0 | |
|
Rowland Water District Los Angeles County |
56,100 | 0 | 0 | |
|
City of West Sacramento West Sacramento · Yolo County |
55,991 | 1 | 1 | |
|
Paramount City, Water Dept. Paramount · Los Angeles County |
55,200 | 0 | 0 | |
|
Gswc Bell, Bell Gardens Los Angeles County |
55,050 | 0 | 0 | |
|
Cal AM Suburban Rosemont Sacramento County |
54,893 | 0 | 0 | |
|
City of Thousand Oaks Water Department Ventura County |
54,770 | 0 | 0 | |
|
Ceres, City of Ceres · Stanislaus County |
54,513 | 1 | 1 | |
|
City of Arcadia Arcadia · Los Angeles County |
54,236 | 0 | 0 | |
|
EL Toro Water District Orange County |
53,415 | 0 | 0 | |
|
Lake Hemet Mwd Riverside County |
52,913 | 0 | 0 | |
|
Yucaipa Valley Water District San Bernardino County |
52,202 | 3 | 0 | |
|
City of San Clemente San Clemente · Orange County |
51,545 | 0 | 0 | |
|
Delano, City of Delano · Kern County |
51,428 | 0 | 0 | |
|
Golden State WC Placentia/yorba Linda Orange County |
50,804 | 0 | 0 | |
|
Cal AM Parkway Sacramento County |
50,646 | 0 | 0 | |
|
Gswc Artesia Los Angeles County |
50,415 | 0 | 0 | |
|
Whittier-City, Water Dept. Whittier · Los Angeles County |
49,954 | 0 | 0 | |
|
Poway, City of Poway · San Diego County |
49,888 | 0 | 0 | |
|
San Luis Obispo Water Department San Luis Obispo County |
49,534 | 0 | 0 | |
|
City of los Banos Los Banos · Merced County |
48,896 | 1 | 0 | |
|
Cal AM Lincoln Oaks Sacramento County |
48,105 | 0 | 0 | |
|
City of San Jose Nsj/alviso San Jose · Santa Clara County |
48,082 | 0 | 0 | |
|
Cal/am Water Company San Marino Los Angeles County |
48,065 | 0 | 0 | |
|
Camarillo Water Dept Ventura County |
47,701 | 0 | 0 | |
|
City of Brea Brea · Orange County |
47,454 | 0 | 0 | |
|
City of Morgan Hill Morgan Hill · Santa Clara County |
47,374 | 0 | 0 | |
|
Golden State Water Co. Cordova Sacramento County |
47,366 | 0 | 0 | |
|
Diablo Water District Contra Costa County |
47,158 | 0 | 0 |
About this data
Rules violated counts the rules a system was in violation of in the past three years, including monitoring and reporting lapses; one rule can carry several violations. Unresolved is the number of those rules still in violation at EPA's latest data refresh.
Source: the U.S. EPA's Enforcement and Compliance History Online system (ECHO), which publishes the federal Safe Drinking Water Information System. EPA's terms and values are shown as published. The California records are from EPA's data refresh of Oct 7, 2026; EPA refreshes this data quarterly, and states report to EPA with a lag of three to six months, so the newest violations may not appear yet. Retrieved from ECHO on Oct 11, 2026.