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EWG's Tap Water Database

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Chloroform

Homer

Chloroform, one of the total trihalomethanes (TTHMs), is formed when chlorine or other disinfectants are used to treat drinking water. Chloroform and other disinfection byproducts increase the risk of cancer and may cause problems during pregnancy. Read More.

In addition to tap water disinfection, chloroform pollution in the environment also comes from industrial discharges from pulp and paper mills, and from urban wastewater effluent. Human studies show that chloroform damages the kidneys, liver and central nervous system. In animals, chloroform causes infertility, birth defects and cancer.

Click here to read more about disinfection byproducts.

 

35

Samples

0

Samples exceeding legal limit (MCL)

0

Samples exceeding
health guidelines

Testing results - average by year

 
YearAverage resultSamples takenDetectionsRange of results
20109.80 ppb119.80 ppb
2011ND20ND
2012ND10ND
20133.06 ppb82ND - 23.0 ppb
20147.48 ppb146ND - 49.0 ppb
20157.30 ppb96ND - 48.0 ppb

ppb = parts per billion.

State and national drinking water standards and health guidelines

Health Guideline 0.4 ppb

The health guideline of 0.4 ppb for chloroform was proposed in 2018 by the California Office of Environmental Health Hazard Assessment as a one-in-a-million lifetime risk of cancer. Values greater than one-in-a-million cancer risk level can result in increased cancer cases above one in a million people.

ppb = parts per billion.

EPA Maximum Contaminant
Level Goal (MCLG)70.0 ppb

A non-enforceable federal health guideline. For cancer-causing chemicals, these health goals are typically set to zero.

ppb = parts per billion.

All test results

Date Lab ID Result
2010-08-10AG966779.80 ppb
2011-02-07AH18797ND
2011-02-07AH18796ND
2012-10-09AH81324ND
2013-01-14AH87341ND
2013-04-15AH99049ND
2013-07-08AI05571ND
2013-09-04AI1431023.0 ppb
2013-09-04AI143111.50 ppb
2013-10-08AI20240ND
2013-12-09AI24271ND
2013-12-09AI24270ND
2014-01-08AI26178ND
2014-01-08AI26177ND
2014-01-08AI26176ND
2014-03-04AI29159ND
2014-03-04AI291583.40 ppb
2014-04-14AI37968ND
2014-06-02AI420742.30 ppb
2014-06-02AI4207316.0 ppb
2014-07-08AI45055ND
2014-09-04AI5248717.0 ppb
2014-09-04AI5248649.0 ppb
2014-10-16AI57749ND
2014-12-08AI60853ND
2014-12-08AI6085217.0 ppb
2015-01-12AI62652ND
2015-03-04AI663652.30 ppb
2015-03-04AI663642.30 ppb
2015-06-02AI785512.70 ppb
2015-06-02AI785502.60 ppb
2015-09-03AI88767ND
2015-09-03AI8876648.0 ppb
2015-12-03AJ01952ND
2015-12-03AJ019517.80 ppb