EWG's Tap Water Database — 2021 UPDATE



Clarksville Water Department

Dibromochloromethane, one of the total trihalomethanes (TTHMs), is formed when chlorine or other disinfectants are used to treat drinking water. Dibromochloromethane and other disinfection byproducts increase the risk of cancer and may cause problems during pregnancy. Click here to read more about disinfection byproducts.





Samples exceeding legal limit (MCL)


Samples exceeding
health guidelines

Testing results - average by year

YearAverage resultSamples takenDetectionsRange of results
20140.552 ppb110.552 ppb
20150.771 ppb110.771 ppb
20160.921 ppb110.921 ppb
20170.592 ppb110.592 ppb
20180.859 ppb110.859 ppb
20191.10 ppb111.10 ppb

ppb = parts per billion

State and national drinking water standards and health guidelines

EWG Health Guideline 0.1 ppb

The EWG Health Guideline of 0.1 ppb for dibromochloromethane 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
2014-05-060.552 ppb
2015-09-010.771 ppb
2016-10-060.921 ppb
2017-09-210.592 ppb
2018-09-130.859 ppb
2019-09-061.10 ppb