Know Your Environment. Protect Your Health.

Chlorate

Tualatin Valley 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.

 

20

Samples

0

Samples exceeding legal limit (MCL)

1

Samples exceeding
health guidelines

Testing results - average by year

 
YearAverage resultSamples takenDetectionsRange of results
201411.5 ppb102ND - 95.0 ppb
201526.0 ppb101ND - 260.0 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
2014-08-13201408140547AMND
2014-08-13201408140326AM20.0 ppb
2014-08-13201408140336AMND
2014-08-13201408140405AMND
2014-08-13201408140329AM95.0 ppb
2014-08-13201408140528AMND
2014-11-18201411190458AMND
2014-11-18201411190460AMND
2014-11-18201411190462AMND
2014-11-18201411190456AMND
2015-02-24201502260475AMND
2015-02-25201502260455AMND
2015-02-25201502260316AMND
2015-02-25201502260208AMND
2015-06-29201506300318AM260.0 ppb
2015-06-29201506300316AMND
2015-06-29201506300309AMND
2015-06-29201506300446AMND
2015-06-29201506300295AMND
2015-06-29201506300303AMND