Know Your Environment. Protect Your Health.

Chlorate

City of Sunnyside

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)

3

Samples exceeding
health guidelines

Testing results - average by year

 
YearAverage resultSamples takenDetectionsRange of results
201475.2 ppb208ND - 310.0 ppb
2015N/A00N/A
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
2014-03-31WA97-SE1-14-05465-13407ND
2014-03-31WA97-SE1-14-05465-13409ND
2014-03-31WA97-SE1-14-05465-13414ND
2014-03-31WA97-SE1-14-05465-13413179.0 ppb
2014-03-31WA97-SE1-14-05465-1341138.0 ppb
2014-03-31WA97-SE1-14-05465-13412167.0 ppb
2014-03-31WA97-SE1-14-05465-1341582.0 ppb
2014-03-31WA97-SE1-14-05465-13408ND
2014-03-31WA97-SE1-14-05465-13410ND
2014-03-31WA97-SE1-14-05465-13406ND
2014-09-03WA97-SE2-14-17266-39556ND
2014-09-03WA97-SE2-14-17266-39554ND
2014-09-03WA97-SE2-14-17266-39553ND
2014-09-03WA97-SE2-14-17266-39553AND
2014-09-03WA97-SE2-14-17266-39557305.0 ppb
2014-09-03WA97-SE2-14-17795-40725233.0 ppb
2014-09-03WA97-SE2-14-17266-39558310.0 ppb
2014-09-03WA97-SE2-14-17266-39559ND
2014-09-03WA97-SE2-14-17266-39555ND
2014-09-03WA97-SE2-14-17795-40724189.0 ppb