EWG's Tap Water Database — 2019 UPDATE


Trichloroacetic acid

Waukesha Water Utility

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
20120.244 ppb75ND - 0.430 ppb
20130.385 ppb220.300 ppb - 0.470 ppb
20140.725 ppb220.700 ppb - 0.750 ppb
20150.160 ppb21ND - 0.320 ppb
20160.475 ppb220.460 ppb - 0.490 ppb
20170.676 ppb330.541 ppb - 0.858 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
2012-08-026762010.290 ppb
2012-08-026762050.300 ppb
2012-08-026762020.300 ppb
2012-08-026762040.390 ppb
2012-08-026762060.430 ppb
2013-08-277401510.300 ppb
2013-08-277401520.470 ppb
2014-08-128105260.700 ppb
2014-08-128105250.750 ppb
2015-08-318796110.320 ppb
2016-07-149333770.460 ppb
2016-07-149333760.490 ppb
2017-07-031707308-002B0.541 ppb
2017-07-031707308-001B0.858 ppb
2017-10-1110239340.630 ppb