waterbycounty

California Water Quality

Drinking water data for all 58 counties.

Avg Water Score

99.8

State Grade

A

Counties with Data

58

of 58 total

All California Counties

CountyWater Score
Alameda County100.0
Butte County100.0
El Dorado County100.0
Glenn County100.0
Humboldt County100.0
Lassen County100.0
Los Angeles County100.0
Marin County100.0
Nevada County100.0
Orange County100.0
Placer County100.0
Riverside County100.0
Sacramento County100.0
San Diego County100.0
San Francisco County100.0
San Mateo County100.0
Santa Barbara County100.0
Santa Clara County100.0
Ventura County100.0
Yuba County100.0
Calaveras County99.9
Contra Costa County99.9
Del Norte County99.9
Fresno County99.9
Imperial County99.9
Merced County99.9
San Bernardino County99.9
San Joaquin County99.9
Santa Cruz County99.9
Shasta County99.9
Solano County99.9
Sonoma County99.9
Stanislaus County99.9
Sutter County99.9
Yolo County99.9
Amador County99.8
Kings County99.8
Mendocino County99.8
Napa County99.8
San Benito County99.8
Tuolumne County99.8
Kern County99.7
Modoc County99.7
Mono County99.7
Monterey County99.7
Inyo County99.6
Lake County99.6
Mariposa County99.6
Plumas County99.6
Sierra County99.6
Siskiyou County99.6
San Luis Obispo County99.5
Tulare County99.5
Trinity County99.3
Tehama County99.1
Alpine County99.0
Colusa County98.9
Madera County98.2

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Data Source

Water quality data sourced from the EPA Safe Drinking Water Information System (SDWIS) via the ECHO enforcement database. Scores reflect compliance history and health-based violation counts.

Disclaimer: This data is informational only. It is not health, legal, or professional advice. For concerns about your specific water supply, contact your local water utility.

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