Chlorate
Westbury WD
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.
Testing results - average by year
Year | Average result | Samples taken | Detections | Range of results |
---|---|---|---|---|
2013 | 7.36 ppb | 11 | 3 | ND - 32.0 ppb |
2014 | 24.3 ppb | 11 | 8 | ND - 55.0 ppb |
2015 | N/A | 0 | 0 | N/A |
2016 | N/A | 0 | 0 | N/A |
2017 | N/A | 0 | 0 | N/A |
2018 | N/A | 0 | 0 | N/A |
2019 | N/A | 0 | 0 | N/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 |
---|---|---|
2013-07-22 | 07353 | ND |
2013-07-22 | 08007 | ND |
2013-07-22 | 13192 | 32.0 ppb |
2013-07-22 | 48279 | ND |
2013-07-22 | 05007 | ND |
2013-07-23 | 08497 | ND |
2013-07-23 | 05654 | ND |
2013-07-23 | 02602 | 22.0 ppb |
2013-10-01 | 10451 | 27.0 ppb |
2013-10-01 | 07785 | ND |
2013-10-01 | 00101 | ND |
2014-01-30 | UCMR3 10451 | 48.0 ppb |
2014-01-30 | UCMR3 05007 | 30.0 ppb |
2014-01-30 | UCMR3 13192 | 23.0 ppb |
2014-01-30 | UCMR3 48279 | 24.0 ppb |
2014-01-30 | UCMR3 02602 | 33.0 ppb |
2014-01-30 | UCMR3 07353 | 55.0 ppb |
2014-01-30 | UCMR3 07785 | ND |
2014-01-30 | UCMR3 05654 | 24.0 ppb |
2014-01-30 | UCMR3 08497 | 30.0 ppb |
2014-03-30 | UCMR3 00101 | ND |
2014-08-21 | 08007 082014 | ND |