Menu

EWG's Tap Water Database — 2019 UPDATE

Donate

Chlorate

New York City System

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.

 

30

Samples

0

Samples exceeding legal limit (MCL)

0

Samples exceeding
health guidelines

Testing results - average by year

 
YearAverage resultSamples takenDetectionsRange of results
2012N/A00N/A
2013ND50ND
20148.42 ppb195ND - 39.0 ppb
201582.0 ppb6644.0 ppb - 130.0 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
2013-12-10201312110711AMND
2013-12-10201312110762AMND
2013-12-10201312110609AMND
2013-12-10201312110565AMND
2013-12-10201312110548AMND
2014-01-15201401160374AMND
2014-03-11201403120550AMND
2014-03-11201403120478AMND
2014-03-11201403120580AMND
2014-03-11201403120556AMND
2014-03-11201403120582AMND
2014-03-11201403120608AMND
2014-06-24201406250156AM33.0 ppb
2014-06-24201406250127AMND
2014-06-24201406250381AM39.0 ppb
2014-06-24201406250133AMND
2014-06-24201406250148AM39.0 ppb
2014-06-24201406250135AMND
2014-09-23201409240312AM25.0 ppb
2014-09-23201409240402AMND
2014-09-23201409240320AM24.0 ppb
2014-09-23201409240346AMND
2014-09-23201409240447AMND
2014-09-23201409240450AMND
2015-06-25201505020407AM66.0 ppb
2015-06-25201505020409AM83.0 ppb
2015-09-23201508080114AM72.0 ppb
2015-09-23201508080112AM130.0 ppb
2015-12-08201511070106AM97.0 ppb
2015-12-08201511070108AM44.0 ppb