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EWG's Tap Water Database — 2019 UPDATE

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Chloroform

Marshall Waterworks

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.

 

19

Samples

0

Samples exceeding legal limit (MCL)

7

Samples exceeding
health guidelines

Testing results - average by year

 
YearAverage resultSamples takenDetectionsRange of results
2012ND40ND
20130.888 ppb83ND - 2.80 ppb
20140.203 ppb41ND - 0.810 ppb
20151.40 ppb111.40 ppb
20160.600 ppb110.600 ppb
20172.10 ppb112.10 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
2012-06-19OW004720ND
2012-06-19OW004719ND
2012-09-10OX000854ND
2012-11-05OX001574ND
2013-02-12OX002419ND
2013-02-12OX002418ND
2013-02-12OX002417ND
2013-04-02OX002886ND
2013-07-01OY000002ND
2013-07-08OY0000551.60 ppb
2013-07-08OY0000572.80 ppb
2013-07-08OY0000562.70 ppb
2014-02-05118447001ND
2014-02-11119095001ND
2014-02-19120152001ND
2014-07-151452170010.810 ppb
2015-08-118763111.40 ppb
2016-09-149458450.600 ppb
2017-07-2510066072.10 ppb