Menu

EWG's Tap Water Database — 2019 UPDATE

Donate

Chlorate

West Sound Utility District #1

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.

 

36

Samples

0

Samples exceeding legal limit (MCL)

4

Samples exceeding
health guidelines

Testing results - average by year

 
YearAverage resultSamples takenDetectionsRange of results
2012N/A00N/A
2013N/A00N/A
2014126.2 ppb1813ND - 350.0 ppb
201559.8 ppb1813ND - 410.0 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
2014-09-22201409240534AM200.0 ppb
2014-09-22201409240416AMND
2014-09-22201409240418AM38.0 ppb
2014-09-22201409240412AM320.0 ppb
2014-09-22201409240477AM200.0 ppb
2014-09-22201409240400AM190.0 ppb
2014-09-23201409250525AMND
2014-09-23201409250596AM190.0 ppb
2014-09-23201409250638AMND
2014-09-23201409250515AM350.0 ppb
2014-09-24201409260328AMND
2014-09-24201409260313AM74.0 ppb
2014-09-24201409260302AM52.0 ppb
2014-09-24201409260275AM100.0 ppb
2014-09-24201409260271AMND
2014-09-24201409260300AM300.0 ppb
2014-09-24201409260268AM78.0 ppb
2014-09-24201409260273AM180.0 ppb
2015-03-16201503180471AM46.0 ppb
2015-03-16201503180707AM130.0 ppb
2015-03-16201503180807AMND
2015-03-16201503180809AM32.0 ppb
2015-03-16201503180434AM45.0 ppb
2015-03-16201503180580AM60.0 ppb
2015-03-16201503180741AM44.0 ppb
2015-03-16201503180569AMND
2015-03-17201503190607AM47.0 ppb
2015-03-17201503190483AM37.0 ppb
2015-03-17201503190660AM72.0 ppb
2015-03-17201503190512AM410.0 ppb
2015-03-17201503190566AMND
2015-03-17201503190658AM48.0 ppb
2015-03-18201503200132AM53.0 ppb
2015-03-18201503200142AM53.0 ppb
2015-03-18201503200254AMND
2015-03-18201503200243AMND