Monochloroacetic acid

Wilton, City of

Monochloroacetic 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.

MORE ABOUT THIS CONTAMINANT

Samples

Samples exceeding legal limit (MCL)

Samples exceeding
health guidelines

Testing results - average by year

Year	Average result	Samples taken	Detections	Range of results
2014	ND	4	0	ND
2015	ND	4	0	ND
2016	0.638 ppb	4	1	ND - 2.55 ppb
2017	0.655 ppb	4	1	ND - 2.62 ppb
2018	0.913 ppb	4	1	ND - 3.65 ppb
2019	ND	4	0	ND

ppb = parts per billion

State and national drinking water standards and health guidelines

EWG Health Guideline 53 ppb

The EWG Health Guideline of 53 ppb for monochloroacetic 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.. This health guideline protects against system toxicity.

ppb = parts per billion

All test results

Date	Lab ID	Result
2014-02-18	14-S241	ND
2014-05-20	14-S814	ND
2014-08-19	14-S2036	ND
2014-11-17	14-S2746	ND
2015-02-18	15-S194	ND
2015-05-19	15-S741	ND
2015-08-18	15-S1752	ND
2015-11-16	15-S2451	ND
2016-02-17	16-S187	ND
2016-05-17	16-S943	ND
2016-08-23	16-S2188	ND
2016-11-15	16-S2840	2.55 ppb
2017-02-21	17-S321	2.62 ppb
2017-05-15	17-S769	ND
2017-08-21	17-S1731	ND
2017-11-13	17-S2361	ND
2018-02-13	18-S199	ND
2018-05-15	18-S695	3.65 ppb
2018-08-21	18-S1765	ND
2018-11-14	18-S2369	ND
2019-02-11	19-S186	ND
2019-05-16	19-S649	ND
2019-08-19	19-S1668	ND
2019-11-12	19-S2425	ND