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EWG's Tap Water Database — 2021 UPDATE

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Chloroform

Medfield Water Department

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.

MORE ABOUT THIS CONTAMINANT

 

128

Samples

0

Samples exceeding legal limit (MCL)

19

Samples exceeding
health guidelines

Testing results - average by year

 
YearAverage resultSamples takenDetectionsRange of results
20140.0182 ppb331ND - 0.600 ppb
20150.462 ppb347ND - 4.30 ppb
20160.0429 ppb211ND - 0.900 ppb
20170.175 ppb122ND - 1.20 ppb
20180.486 ppb144ND - 3.10 ppb
20190.536 ppb144ND - 3.40 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 Result
2014-03-050.600 ppb
2014-03-05ND
2014-03-05ND
2014-03-24ND
2014-03-24ND
2014-03-24ND
2014-04-02ND
2014-04-02ND
2014-04-02ND
2014-05-21ND
2014-05-21ND
2014-05-21ND
2014-06-18ND
2014-06-18ND
2014-06-18ND
2014-07-16ND
2014-07-16ND
2014-07-16ND
2014-08-06ND
2014-08-06ND
2014-08-06ND
2014-09-03ND
2014-09-03ND
2014-09-03ND
2014-10-01ND
2014-10-01ND
2014-10-01ND
2014-11-05ND
2014-11-05ND
2014-11-05ND
2014-12-03ND
2014-12-03ND
2014-12-03ND
2015-02-041.90 ppb
2015-02-043.10 ppb
2015-02-041.40 ppb
2015-02-042.90 ppb
2015-02-27ND
2015-02-27ND
2015-02-27ND
2015-03-114.30 ppb
2015-05-06ND
2015-05-06ND
2015-05-06ND
2015-06-03ND
2015-06-03ND
2015-06-03ND
2015-07-15ND
2015-07-15ND
2015-07-15ND
2015-08-05ND
2015-08-05ND
2015-08-05ND
2015-08-19ND
2015-08-191.30 ppb
2015-09-02ND
2015-09-02ND
2015-09-02ND
2015-10-210.800 ppb
2015-10-21ND
2015-10-21ND
2015-11-04ND
2015-11-04ND
2015-11-04ND
2015-12-16ND
2015-12-16ND
2015-12-16ND
2016-01-20ND
2016-01-20ND
2016-01-20ND
2016-02-03ND
2016-02-03ND
2016-02-03ND
2016-03-02ND
2016-03-02ND
2016-03-02ND
2016-05-19ND
2016-06-15ND
2016-06-15ND
2016-06-15ND
2016-08-03ND
2016-08-030.900 ppb
2016-09-07ND
2016-09-07ND
2016-09-07ND
2016-10-05ND
2016-10-05ND
2016-10-05ND
2017-02-151.20 ppb
2017-02-15ND
2017-02-150.900 ppb
2017-06-07ND
2017-06-07ND
2017-06-07ND
2017-09-06ND
2017-09-06ND
2017-09-06ND
2017-11-15ND
2017-11-15ND
2017-11-15ND
2018-03-280.700 ppb
2018-03-282.30 ppb
2018-03-280.700 ppb
2018-05-16ND
2018-05-16ND
2018-05-16ND
2018-08-01ND
2018-08-013.10 ppb
2018-08-15ND
2018-08-15ND
2018-08-15ND
2018-10-30ND
2018-10-30ND
2018-10-30ND
2019-03-200.600 ppb
2019-03-202.30 ppb
2019-03-201.20 ppb
2019-06-17ND
2019-06-17ND
2019-06-17ND
2019-07-17ND
2019-07-17ND
2019-07-17ND
2019-08-07ND
2019-08-073.40 ppb
2019-11-05ND
2019-11-05ND
2019-11-05ND