Safest Drinking Water in California 2026
California has 5 public water systems serving 2,798,397 people. The safest system is East Bay MUD in Oakland with a score of 100/100.
Top 5 Water Systems in California
| # | Water System | City | Pop. Served | Source | Violations | Score |
|---|---|---|---|---|---|---|
| 1 | East Bay MUD | Oakland | 1,442,800 | Surface water | 0 | A (100) |
| 2 | Alameda County Water District | Fremont | 344,000 | Surface water | 0 | A (100) |
| 3 | CWS - Bakersfield | San Jose | 267,881 | Surface water | 0 | A (100) |
| 4 | Contra Costa Water District | Concord | 198,000 | Surface water | 0 | A (100) |
| 5 | City of Fresno | Fresno | 545,716 | Surface water | 0 | A (94) |
Water quality data for California is sourced from the EPA Safe Drinking Water Information System (SDWIS), which tracks compliance for all public water systems.
Frequently Asked Questions
East Bay MUD in Oakland has the highest Water Safety Score in California at 100/100 (Grade A), serving 1,442,800 people.
California has 5 public water systems serving 2,798,397 people. The average Water Safety Score is 99/100.
The Water Safety Score (0-100) is based on health violations (40%), contaminant exceedances (30%), enforcement history (20%), and monitoring violations (10%). Higher scores mean cleaner, safer water.
Water Safety Score: health violations (40%), contaminant exceedances (30%), enforcement history (20%), monitoring violations (10%).