EWG's Tap Water Database


Trichloroacetic acid

South Hero Fire District 4

Trichloroacetic acid, one of the group of five haloacetic acids regulated by federal standards, is formed when chlorine or other disinfectants are used to treat drinking water. Haloacetic acids 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
201017.3 ppb663.00 ppb - 28.0 ppb
201113.8 ppb440.0250 ppb - 20.0 ppb
201221.5 ppb4417.0 ppb - 26.0 ppb
201321.8 ppb4416.0 ppb - 33.0 ppb
201425.0 ppb4420.0 ppb - 31.0 ppb
201528.8 ppb4422.0 ppb - 36.0 ppb

ppb = parts per billion.

State and national drinking water standards and health guidelines

Health Guideline 0.5 ppb

The health guideline of 0.5 ppb for trichloroacetic acid was defined by the Environmental Protection Agency 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)20.0 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
2010-02-0410S2813.00 ppb
2010-02-0410S28015.0 ppb
2010-02-0410S27914.0 ppb
2010-06-1810S39528.0 ppb
2010-09-1411S06023.0 ppb
2010-12-1411S09621.0 ppb
2011-03-2811S11920.0 ppb
2011-06-2611S14616.0 ppb
2011-09-2312S0960.0250 ppb
2011-12-0512S11119.0 ppb
2012-03-0712S16520.0 ppb
2012-05-1412S18623.0 ppb
2012-09-1713S0010217.0 ppb
2012-12-1113S0014126.0 ppb
2013-03-0613S0018518.0 ppb
2013-05-1413S0021320.0 ppb
2013-08-1814S0005116.0 ppb
2013-11-0614S0009733.0 ppb
2014-02-0414S0012420.0 ppb
2014-05-2214S0016525.0 ppb
2014-08-2015S0009024.0 ppb
2014-11-0515S0014031.0 ppb
2015-02-0415S0016235.0 ppb
2015-05-2615S0020636.0 ppb
2015-08-0716S0002222.0 ppb
2015-11-1116S0008622.0 ppb