Know Your Environment. Protect Your Health.

Chloroform

Marston PWS

Chloroform, one of the total trihalomethanes (TTHMs), is formed when chlorine or other disinfectants are used to treat drinking water. Chloroform and other disinfection byproducts increase the risk of cancer and may cause problems during pregnancy. Read More.

In addition to tap water disinfection, chloroform pollution in the environment also comes from industrial discharges from pulp and paper mills, and from urban wastewater effluent. Human studies show that chloroform damages the kidneys, liver and central nervous system. In animals, chloroform causes infertility, birth defects and cancer.

Click here to read more about disinfection byproducts.

 

46

Samples

0

Samples exceeding legal limit (MCL)

30

Samples exceeding
health guidelines

Testing results - average by year

 
YearAverage resultSamples takenDetectionsRange of results
20186.96 ppb553.35 ppb - 12.2 ppb
20195.46 ppb552.43 ppb - 9.17 ppb
20202.86 ppb95ND - 10.6 ppb
20212.92 ppb95ND - 9.79 ppb
20222.73 ppb95ND - 10.4 ppb
20231.79 ppb95ND - 6.25 ppb

ppb = parts per billion

State, National, and Health Guidelines for Drinking Water

EWG Health Guideline: 0.4 ppb

The EWG Health Guideline of 0.4 ppb for chloroform was based on the California Office of Environmental Health Hazard Assessment's public health goal, the level of a drinking water contaminant that does not pose a significant health risk. This health guideline protects against cancer and harm to fetal growth and development.

ppb = parts per billion

All test results

Date Lab ID Result
2018-03-06AD175239.70 ppb
2018-05-02AD1867112.2 ppb
2018-07-11AD295903.35 ppb
2018-07-25AD292895.62 ppb
2018-10-11AD350683.93 ppb
2019-01-08AD383813.31 ppb
2019-04-10AD466729.17 ppb
2019-07-11AD527172.43 ppb
2019-08-14AD519075.95 ppb
2019-10-17AD573796.44 ppb
2020-01-12AD60698ND
2020-01-12AD606992.29 ppb
2020-04-1420043021.72 ppb
2020-04-142004303ND
2020-07-1520117743.04 ppb
2020-07-152012319ND
2020-08-31201177310.6 ppb
2020-10-1820166448.07 ppb
2020-10-182016645ND
2021-01-1020202431.76 ppb
2021-01-102020244ND
2021-04-122103857ND
2021-04-1221038561.74 ppb
2021-07-112113867ND
2021-07-1121138664.01 ppb
2021-07-1521138659.01 ppb
2021-10-182118176ND
2021-10-1821181759.79 ppb
2022-01-122121678ND
2022-01-1221216771.23 ppb
2022-04-132204415ND
2022-04-1322044141.78 ppb
2022-07-182214868ND
2022-07-1822148671.53 ppb
2022-07-24221486610.4 ppb
2022-10-102219710ND
2022-10-1022197099.59 ppb
2023-01-0822233781.81 ppb
2023-01-082223379ND
2023-04-1223035446.25 ppb
2023-04-122303545ND
2023-07-1923117762.01 ppb
2023-07-192311777ND
2023-07-3023117753.64 ppb
2023-10-182316888ND
2023-10-1823168872.38 ppb