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EWG's Tap Water Database — 2019 UPDATE

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Bromate

Contra Costa Water District

Bromate is a carcinogenic disinfection byproduct formed when source waters containing bromide are treated with ozonation or sodium hypochlorite. Studies of laboratory animals show that bromate damages DNA and causes cancer in multiple organs. Click here to read more about disinfection byproducts.

 

54

Samples

1

Samples exceeding legal limit (MCL)

8

Samples exceeding
health guidelines

Testing results - average by year

 
YearAverage resultSamples takenDetectionsRange of results
2012ND80ND
20130.610 ppb102ND - 3.20 ppb
20143.22 ppb103ND - 16.0 ppb
20150.622 ppb91ND - 5.60 ppb
2016ND80ND
20171.21 ppb92ND - 5.80 ppb

ppb = parts per billion

State and national drinking water standards and health guidelines

EWG Health Guideline 0.1 ppb

The EWG Health Guideline of 0.1 ppb for bromate was defined by the California Office of Environmental Health Hazard Assessment as a public health goal, the level of a drinking water contaminant that does not pose a significant health risk. This health guideline protects against cancer.

EPA Maximum Contaminant
Level (MCL) 10 ppb

The legal limit for bromate, established in 1998, was based on analytical detection limits at the time that the standard was set. This limit may not fully protect against the risk of cancer due to bromate exposure.

ppb = parts per billion

All test results

Date Lab ID Result
2012-04-192473-003-0830ND
2012-05-222473-003-1040ND
2012-06-052473-003-1320ND
2012-07-242473-003-0825ND
2012-08-212473-003-0830ND
2012-09-042473-003-0745ND
2012-10-162473-003-0910ND
2012-11-209590-003-1120ND
2013-03-202473-003-1255ND
2013-04-162473-003-0815ND
2013-05-219590-003-07303.20 ppb
2013-06-049590-003-13452.90 ppb
2013-07-239590-003-0805ND
2013-08-199590-003-0925ND
2013-09-039590-003-0910ND
2013-10-229590-003-0625ND
2013-11-199590-003-0540ND
2013-12-039590-003-0805ND
2014-03-109590-003-1119ND
2014-04-229590-003-083616.0 ppb
2014-05-279590-003-0810ND
2014-06-039590-003-144510.00 ppb
2014-07-229590-003-09006.20 ppb
2014-08-199590-003-0835ND
2014-09-029590-003-1500ND
2014-10-212473-003-0900ND
2014-11-182473-003-0830ND
2014-12-022473-003-1345ND
2015-03-182473-003-1429ND
2015-04-212473-003-0905ND
2015-05-192473-003-09205.60 ppb
2015-06-022473-003-0815ND
2015-07-212473-003-0809ND
2015-08-182473-003-1403ND
2015-09-092473-003-1330ND
2015-10-132473-003-0900ND
2015-11-102473-003-0945ND
2016-05-172473-003-0900ND
2016-06-072473-003-0900ND
2016-07-192473-003-0900ND
2016-08-099590-003-0838ND
2016-09-069590-003-0823ND
2016-10-112473-003-0900ND
2016-11-082473-003-0900ND
2016-12-062473-003-0900ND
2017-04-179590-003-1000ND
2017-04-172473-003-0945ND
2017-05-089590-003-1305ND
2017-06-069590-003-1315ND
2017-07-189590-003-0848ND
2017-08-159590-003-1110ND
2017-09-129590-003-14205.80 ppb
2017-10-109590-003-0950ND
2017-11-149590-003-14505.10 ppb