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EWG's Tap Water Database — 2021 UPDATE

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Chlorate

Ward II Water District

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.

MORE ABOUT THIS CONTAMINANT

 

36

Samples

0

Samples exceeding legal limit (MCL)

0

Samples exceeding
health guidelines

Testing results - average by year

 
YearAverage resultSamples takenDetectionsRange of results
2013ND180ND
2014ND180ND
2015N/A00N/A
2016N/A00N/A
2017N/A00N/A
2018N/A00N/A
2019N/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
2013-09-1635108510005AMND
2013-09-1635108510001AMND
2013-09-1635108510011AMND
2013-09-1635108510019AMND
2013-09-1635108510015AMND
2013-09-1635108510002AMND
2013-09-1635108510004AMND
2013-09-1635108510007AMND
2013-09-1635108510013AMND
2013-09-1635108510009AMND
2013-09-1635108510012AMND
2013-09-1635108510017AMND
2013-09-1635108510020AMND
2013-09-1635108510006AMND
2013-09-1635108510008AMND
2013-09-1635108510003AMND
2013-09-1635108510021AMND
2013-09-1635108510010AMND
2014-02-18MEYERS WELL POEND
2014-02-18STAFFORDWELL POEND
2014-02-18BUDDY ELLIS WELLND
2014-02-18BALL PARK WELL PND
2014-02-18BURGESS WELL POEND
2014-02-18HWY 190 WELL POEND
2014-02-18TOWER WELL POEND
2014-02-18MCCLURE WELL POEND
2014-02-18BUDDY ELLIS WELLND
2014-02-18AMITE CHURCH & HND
2014-02-18STEVE HUGHES RDND
2014-02-18KEM LANE @ HWY 6ND
2014-02-18MERGENTS GAS @ HND
2014-02-18NORTH CORBIN SCHND
2014-02-18VERSAILLIES WELLND
2014-02-18ARTIE PEIRSON POND
2014-02-18MELROSE WELL POEND
2014-02-18BRADFORD WELL POND