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National Drinking Water Database

Chlorate in California

Chlorate is a disinfection byproduct (unregulated chlorine dioxide byproduct), an herbicide and a pollutant from explosives.

The Most Polluted Communities in California

31 water utilities reported detecting Chlorate in tap water since 2004, according to EWG's analysis of water quality data supplied by state water agencies

Ranked by highest average Chlorate level

RankSystem Population Served Positive test results of total reported tests Average Level
1Randall-Bold Water Treatment Plant
Oakley, Ca, CA
30,0009 of 9380.11 ppb
(55 to 690 ppb)
2Diablo Water District
Oakley, CA
33,2509 of 9380.11 ppb
(55 to 690 ppb)
3San Diego County Water Authority
San Diego, CA
03 of 3292.67 ppb
(220 to 350 ppb)
4Santa FE I.D.
Rancho Santa Fe, CA
20,82817 of 17238 ppb
(21 to 389 ppb)
5Los Angeles Department of Water and Power
Los Angeles, CA
3,828,7008 of 8235.5 ppb
(85 to 331 ppb)
6Cal AM Water Company - Monterey
Pacific Grove, CA
92,11539 of 39183.97 ppb
(15 to 330 ppb)
7Zone 7 Water Agency
Livermore, CA
195,23091 of 98173.66 ppb
(0 to 534 ppb)
8Alameda County Water District
Fremont, CA
271,0002 of 2168.5 ppb
(137 to 200 ppb)
9San Francisco Regional Water
San Francisco, CA
2,500,0001 of 1163 ppb
(163 ppb)
10City of Escondido
Escondido, CA
140,0001 of 1160 ppb
(160 ppb)

Health Based Limits for Chlorate

There are no health based standards that EWG is using for this chemical

Violation Summary for Chlorate in California

There are no violations reported for this contaminant in California