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EWG's Tap Water Database — 2019 UPDATE

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Chlorate

Dalton Utilities

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.

 

24

Samples

0

Samples exceeding legal limit (MCL)

1

Samples exceeding
health guidelines

Testing results - average by year

 
YearAverage resultSamples takenDetectionsRange of results
2012N/A00N/A
2013N/A00N/A
2014N/A00N/A
201542.1 ppb248ND - 277.0 ppb
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
2015-03-0435178480001AMND
2015-03-0435178480003AM135.0 ppb
2015-03-0935178704001AM137.0 ppb
2015-03-3135181774005AMND
2015-03-3135181774003AMND
2015-03-3135181774001AM65.3 ppb
2015-06-0935192388005AM84.5 ppb
2015-06-0935192388011AM57.8 ppb
2015-06-0935192388007AMND
2015-06-0935192388003AMND
2015-06-0935192388001AM95.9 ppb
2015-06-0935192388009AMND
2015-09-0935206664003AMND
2015-09-0935206663003AMND
2015-09-0935206664001AMND
2015-09-0935206665003AMND
2015-09-0935206663001AM159.0 ppb
2015-09-0935206665001AMND
2015-12-0835220221012AMND
2015-12-0835220221008AMND
2015-12-0835220221010AMND
2015-12-0835220221006AMND
2015-12-0835220221001AMND
2015-12-0835220221003AM277.0 ppb