California water quality
California has 7,862 active public water systems (19,626 on file total), 3,059 of them graded by TapGraded.
Grade distribution
Biggest water systems
LOS ANGELES-CITY, DEPT. OF WATER & POWER
LOS ANGELES, CA · 3,875,566 served
EAST BAY MUD
OAKLAND, CA · 1,442,800 served
SAN DIEGO, CITY OF
SAN DIEGO, CA · 1,385,379 served
SAN JOSE WATER
SAN JOSE, CA · 1,039,920 served
SFPUC CITY DISTRIBUTION DIVISION
BURLINGAME, CA · 848,019 served
EASTERN MUNICIPAL WD
PERRIS, CA · 666,581 served
CITY OF FRESNO
FRESNO, CA · 545,716 served
CITY OF SACRAMENTO MAIN
SACRAMENTO, CA · 527,979 served
LONG BEACH UTILITIES DEPARTMENT
LONG BEACH, CA · 466,772 served
IRVINE RANCH WATER DISTRICT
IRVINE, CA · 444,800 served
Lowest-graded systems
Active, graded systems serving at least 10,000 people, ordered by lowest Tap Grade first.
Pala North
Pala, CA · 14,280 served
LINDSAY, CITY OF
LINDSAY, CA · 12,659 served
YUCAIPA VALLEY WATER DISTRICT
YUCAIPA, CA · 52,010 served
SUISUN-SOLANO WATER AUTHORITY
VACAVILLE, CA · 29,105 served
AVENAL, CITY OF
AVENAL, CA · 13,696 served
LEMOORE, CITY OF
LEMOORE, CA · 27,185 served
MCFARLAND, CITY OF
MCFARLAND, CA · 14,161 served
SCWA - LAGUNA/VINEYARD
SACRAMENTO, CA · 184,896 served
PORTERVILLE, CITY OF
PORTERVILLE, CA · 63,487 served
CERES, CITY OF
CERES, CA · 54,513 served
Cities in California
Source: EPA SDWIS/ECHO · Data as of 2026Q2