EWG's Tap Water Database — 2019 UPDATE


Trichloroacetic acid

Osage City, City of

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
20128.95 ppb444.50 ppb - 19.0 ppb
20135.78 ppb444.60 ppb - 7.40 ppb
20146.18 ppb444.10 ppb - 8.70 ppb
201512.0 ppb1112.0 ppb
20168.80 ppb118.80 ppb
20174.90 ppb114.90 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 trichloroacetic acid was proposed in 2020 by the California Office of Environmental Health Hazard Assessment as a public health goal, the level of a drinking water contaminant that does not pose a significant health risk.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
2012-03-05576065DF5.30 ppb
2012-05-21579036DF19.0 ppb
2012-08-27584606DF7.00 ppb
2012-12-18588836DF4.50 ppb
2013-03-04592857DF4.60 ppb
2013-06-03596852DF6.10 ppb
2013-08-26602098DF7.40 ppb
2013-11-12605440DF5.00 ppb
2014-03-10748334.10 ppb
2014-06-091250475.70 ppb
2014-09-081897758.70 ppb
2014-12-152467396.20 ppb
2015-09-2240969012.0 ppb
2016-09-136218328.80 ppb
2017-09-278478674.90 ppb