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EWG's Tap Water Database — 2019 UPDATE

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Chlorate

Moore

Chlorate forms in drinking water as a byproduct of disinfection. Chlorate impairs thyroid function, making chlorate exposure most harmful during pregnancy and childhood. Read More.

In 2002, California scientists proposed an advisory value, called an action level, for chlorate at 200 parts per billion. Between 2013 and 2015, the EPA collected data through the Unregulated Contaminant Monitoring Rule program and found that over 15 percent of water tests from 38 percent of utilities had chlorate levels above a health-protective concentration, which federal scientists defined as 210 parts per billion, nearly equivalent to the California advisory value.

Click here to read more about disinfection byproducts.

 

47

Samples

0

Samples exceeding legal limit (MCL)

0

Samples exceeding
health guidelines

Testing results - average by year

 
YearAverage resultSamples takenDetectionsRange of results
2012N/A00N/A
2013ND220ND
2014ND220ND
2015ND30ND
2016N/A00N/A
2017N/A00N/A

ppb = parts per billion

State and national drinking water standards and health guidelines

EWG Health Guideline 210 ppb

The EWG Health Guideline of 210 ppb for chlorate was defined by the Environmental Protection Agency as a benchmark for testing under the Unregulated Contaminant Monitoring Rule program. This health guideline protects against hormone disruption.

ppb = parts per billion

All test results

Date Lab ID Result
2013-10-093J10006-25AND
2013-10-093J10006-07AND
2013-10-093J10006-55AND
2013-10-093J10006-40AND
2013-10-093J10006-37AND
2013-10-093J10006-58AND
2013-10-093J10006-46AND
2013-10-093J10006-49AND
2013-10-093J10006-52AND
2013-10-093J10006-43AND
2013-10-093J10006-22AND
2013-10-093J10006-19AND
2013-10-093J10006-04AND
2013-10-093J10006-16AND
2013-10-093J10006-63AND
2013-10-093J10006-13AND
2013-10-093J10006-61AND
2013-10-093J10006-01AND
2013-10-093J10006-34AND
2013-10-093J10006-10AND
2013-10-093J10006-28AND
2013-10-093J10006-31AND
2014-04-074D08021-01ND
2014-04-074D08021-04ND
2014-04-084D09016-07ND
2014-04-084D09016-01ND
2014-04-084D09016-04ND
2014-04-084D09016-10ND
2014-04-084D09016-12ND
2014-04-094D10050-37ND
2014-04-094D10050-43ND
2014-04-094D10050-01ND
2014-04-094D10050-07ND
2014-04-094D10050-04ND
2014-04-094D10050-22ND
2014-04-094D10050-31ND
2014-04-094D10050-25ND
2014-04-094D10050-40ND
2014-04-094D10050-16ND
2014-04-094D10050-34ND
2014-04-094D10050-28ND
2014-04-094D10050-19ND
2014-04-094D10050-10ND
2014-04-094D10050-13ND
2015-12-075L08160-07ND
2015-12-075L08160-04ND
2015-12-075L08160-01ND