Know Your Environment. Protect Your Health.

Chlorate

City of Spokane

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.

 

16

Samples

0

Samples exceeding legal limit (MCL)

0

Samples exceeding
health guidelines

Testing results - average by year

 
YearAverage resultSamples takenDetectionsRange of results
20151.31 ppb161ND - 21.0 ppb
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
2015-03-23WA97-SE1-15-05679-13037ND
2015-03-23WA97-SE1-15-05679-13036ND
2015-03-23WA97-SE1-15-05679-1303921.0 ppb
2015-03-23WA97-SE1-15-05679-13040ND
2015-03-23WA97-SE1-15-05679-13038ND
2015-03-23WA97-SE1-15-05679-13034ND
2015-03-23WA97-SE1-15-05679-13033ND
2015-03-23WA97-SE1-15-05679-13035ND
2015-10-12WA97-SE2-15-22288-49645ND
2015-10-12WA97-SE2-15-22288-49644ND
2015-10-12WA97-SE2-15-22288-49647ND
2015-10-12WA97-SE2-15-22288-49648ND
2015-10-12WA97-SE2-15-22288-49646ND
2015-10-12WA97-SE2-15-22288-49642ND
2015-10-12WA97-SE2-15-22288-49641ND
2015-10-12WA97-SE2-15-22288-49643ND