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National Drinking Water Database

Copper in California

Copper is a naturally occuring metal and drinking water contaminant that enters tap water by corrosion of household plumbing systems and erosion of natural deposits. [read more]

The Most Polluted Communities in California

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

Ranked by highest average Copper level

RankSystem Population Served Positive test results of total reported tests Average Level
1Clear Creek Water Company
Cloverdale, CA
401 of 21850 ppb
(0 to 3700 ppb)
2Evergreen Mobile Estates
Windsor, CA
601 of 1950 ppb
(950 ppb)
3Arnold Park (O Bannon S Mhp)
Hollister, CA
281 of 2800 ppb
(0 to 1600 ppb)
4Creekside Mobilehome Park
Shingletown, CA
701 of 1584 ppb
(584 ppb)
5Delta Bay Club
Isleton, CA
2701 of 1500 ppb
(500 ppb)
6Rural Canyon Mutual Water Company
Forestville, CA
202 of 2343.25 ppb
(26.5 to 660 ppb)
7Lazy B Mobilehome Park
Oakdale, CA
1251 of 2300 ppb
(0 to 600 ppb)
8Gold Beach Park
El Dorado, CA
1001 of 1290 ppb
(290 ppb)
9Las Flores Water Co.
Altadena, CA
4,8541 of 3276.67 ppb
(0 to 830 ppb)
10Elk Creek Community S.D.
Elk Creek, CA
2502 of 2275 ppb
(10 to 540 ppb)

Health Based Limits for Copper

California Public Health GoalsDefined by the State of California Office of Environmental Health Hazard Assessment (OEHHA) as the level of contaminant that is allowed in drinking water. For acutely toxic substances, levels are set at which scientific evidence indicates that no known or anticipated adverse effects on health will occur, plus an adequate margin-of safety. PHGs for carcinogens or other substances which can cause chronic disease shall be based solely on health effects without regard to cost impacts and shall be set at levels which OEHHA has determined do not pose any significant risk to health.300 ppb
National Secondary Drinking Water RegulationsA National Secondary Drinking Water Regulation is a non-enforceable guideline regarding contaminants that may cause cosmetic effects (such as taste, odor, or color). Some states choose to adopt them as enforceable standards. Source: U.S. Environmental Protection Agency. 1000 ppb
Maximum Contaminant Limit Goal (MCLG)A non-enforceable health goal that is set at a level at which no known or anticipated adverse effect on the health of persons occurs and which allows an adequate margin of safety. Source: U.S. Environmental Protection Agency.1300 ppb
EPA Human Health Water Quality CriteriaWater quality criteria set by the US EPA provide guidance for states and tribes authorized to establish water quality standards under the Clean Water Act (CWA) to protect human health. These are non-enforceable standards based upon exposure by both drinking water and the contribution of water contamination to other consumed foods. Source: U.S. Environmental Protection Agency.1300 ppb

Violation Summary for Copper in California

Data from the U.S. Environmental Protection Agency includes the following violations of federal standards in California since 2004

Violation TypeNumber of Violations
Failure to monitor regularly3