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EWG's Tap Water Database — 2021 UPDATE

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Chloroform

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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.

 

48

Samples

0

Samples exceeding legal limit (MCL)

18

Samples exceeding
health guidelines

Testing results - average by year

 
YearAverage resultSamples takenDetectionsRange of results
2013N/A00N/A
20141.91 ppb221.23 ppb - 2.58 ppb
20150.419 ppb205ND - 4.10 ppb
20162.92 ppb221.46 ppb - 4.37 ppb
20172.22 ppb21ND - 4.44 ppb
20180.510 ppb206ND - 5.09 ppb
20192.29 ppb220.760 ppb - 3.81 ppb

ppb = parts per billion

State and national drinking water standards and health guidelines

EWG Health Guideline 0.4 ppb

The EWG 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

All test results

Date Lab ID Result
2014-09-10AC341872.58 ppb
2014-09-10AC341861.23 ppb
2015-01-22AC41399ND
2015-01-22AC414040.690 ppb
2015-01-22AC41397ND
2015-01-22AC41400ND
2015-01-22AC41402ND
2015-01-22AC41413ND
2015-01-22AC41403ND
2015-01-22AC41405ND
2015-01-22AC41409ND
2015-01-22AC41414ND
2015-01-22AC414060.560 ppb
2015-01-22AC414070.580 ppb
2015-01-22AC41410ND
2015-01-22AC41408ND
2015-01-22AC41411ND
2015-01-22AC41412ND
2015-01-22AC41401ND
2015-01-22AC41398ND
2015-08-17AC573742.44 ppb
2015-08-17AC573754.10 ppb
2016-07-19AC797551.46 ppb
2016-07-19AC797564.37 ppb
2017-08-18AD03368ND
2017-08-18AD033694.44 ppb
2018-01-24AD12000ND
2018-01-24AD120160.520 ppb
2018-01-24AD12015ND
2018-01-24AD12014ND
2018-01-24AD12012ND
2018-01-24AD12011ND
2018-01-24AD12010ND
2018-01-24AD12009ND
2018-01-24AD12008ND
2018-01-24AD12007ND
2018-01-24AD120060.540 ppb
2018-01-24AD12005ND
2018-01-24AD12003ND
2018-01-24AD120020.980 ppb
2018-01-24AD12004ND
2018-01-24AD119990.980 ppb
2018-01-24AD11998ND
2018-01-24AD12001ND
2018-08-16AD311712.08 ppb
2018-08-16AD311725.09 ppb
2019-08-27AD538980.760 ppb
2019-08-27AD538993.81 ppb