Know Your Environment. Protect Your Health.

Chlorate

Moscow Water Department

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.

 

20

Samples

0

Samples exceeding legal limit (MCL)

0

Samples exceeding
health guidelines

Testing results - average by year

 
YearAverage resultSamples takenDetectionsRange of results
2014ND100ND
2015ND100ND
2016N/A00N/A
2017N/A00N/A
2018N/A00N/A
2019N/A00N/A
2020N/A00N/A
2021N/A00N/A
2022N/A00N/A
2023N/A00N/A

ppb = parts per billion

State, National, and Health Guidelines for Drinking Water

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
2014-10-03WA97-SE1-14-19853-45085ND
2014-10-03WA97-SE1-14-19853-45084ND
2014-10-03WA97-SE1-14-19853-45084AND
2014-10-03WA97-SE1-14-19853-45082ND
2014-10-03WA97-SE1-14-19853-45086ND
2014-10-03WA97-SE1-14-19853-45088ND
2014-10-03WA97-SE1-14-19853-45091ND
2014-10-03WA97-SE1-14-19853-45090ND
2014-10-03WA97-SE1-14-19853-45089ND
2014-10-03WA97-SE1-14-19853-45087ND
2015-04-0197-SE2-15-06235-14069ND
2015-04-0197-SE2-15-06235-14072ND
2015-04-0197-SE2-15-06235-14071ND
2015-04-0197-SE2-15-06235-14070ND
2015-04-01WA97-SE2-15-06235-14068ND
2015-04-01WA97-SE2-15-06235-14064ND
2015-04-01WA97-SE2-15-06235-14063ND
2015-04-01WA97-SE2-15-06235-14066ND
2015-04-01WA97-SE2-15-06235-14067ND
2015-04-01WA97-SE2-15-06235-14065ND