City Water Quality Rankings in California
601 cities ranked by drinking water quality.
Popular city water quality comparisons
Trending Cities
#121
Royal Oaks
County, CA
100 A
#122 San Bruno
County, CA
100 A
#123 San Clemente
County, CA
100 A
#124 San Fernando
County, CA
100 A
#125 San Joaquin
County, CA
100 A
#126 San Miguel
County, CA
100 A
#127 Santa Clara
County, CA
100 A
#128 Santa Fe Springs
County, CA
100 A
#129 Santa Paula
County, CA
100 A
#130 Sausalito
County, CA
100 A
#131 Seal Beach
County, CA
100 A
#132 Seaside
County, CA
100 A
#133 Sebastopol
County, CA
100 A
#134 Shafter
County, CA
100 A
#135 Shasta
County, CA
100 A
#136 Shasta Lake
County, CA
100 A
#137 Skyforest
County, CA
100 A
#138 Smith River
County, CA
100 A
#139 Soquel
County, CA
100 A
#140 Spring Valley
County, CA
100 A
#141 Stanford
County, CA
100 A
#142 Templeton
County, CA
100 A
#143 Thousand Oaks
County, CA
100 A
#144 Trona
County, CA
100 A
Frequently Asked Questions
How are city water quality rankings calculated in California?
WaterQ city rankings are based on EPA SDWIS data across local public water systems, including contaminant detections, compliance violations, and recency-weighted score signals.
Can I compare two cities in California?
Yes. Use the city comparison links on this page or open the Compare tool to evaluate two cities side by side on score, grade, and water system coverage.
How often does WaterQ refresh city data?
City-level metrics refresh when new EPA data is processed. Check city pages for latest score and violation context.