Menu

EWG's Tap Water Database — 2021 UPDATE

Donate

Chloroform

Norwalk Water Department

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.

MORE ABOUT THIS CONTAMINANT

 

243

Samples

0

Samples exceeding legal limit (MCL)

95

Samples exceeding
health guidelines

Testing results - average by year

 
YearAverage resultSamples takenDetectionsRange of results
2013N/A00N/A
20142.93 ppb288ND - 17.0 ppb
20152.68 ppb4418ND - 13.1 ppb
20162.30 ppb4417ND - 12.4 ppb
20172.66 ppb4417ND - 24.0 ppb
20181.85 ppb4018ND - 6.40 ppb
20191.59 ppb4317ND - 12.4 ppb

ppb = parts per billion

State and national drinking water standards and health guidelines

EWG Health Guideline 0.4 ppb

The EWG Health Guideline of 0.4 ppb for chloroform was proposed in 2018 by the California Office of Environmental Health Hazard Assessment 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

All test results

Date Lab ID Result
2014-02-043761-800-09104.30 ppb
2014-02-043761-801-08156.10 ppb
2014-02-043761-802-08575.10 ppb
2014-02-043761-803-0844ND
2014-02-043761-804-101012.4 ppb
2014-02-043761-805-0950ND
2014-02-043761-806-0935ND
2014-02-043761-807-0830ND
2014-02-199588-002-1030ND
2014-02-199588-003-1000ND
2014-02-199588-012-0930ND
2014-04-299588-002-1029ND
2014-04-299588-003-1018ND
2014-04-299588-012-0950ND
2014-07-239588-002-1025ND
2014-07-239588-003-1010ND
2014-07-239588-012-0945ND
2014-08-123761-800-092510.3 ppb
2014-08-123761-801-083516.0 ppb
2014-08-123761-802-091310.7 ppb
2014-08-123761-803-0900ND
2014-08-123761-804-102017.0 ppb
2014-08-123761-805-1000ND
2014-08-123761-806-0940ND
2014-08-123761-807-0850ND
2014-12-109588-002-1020ND
2014-12-109588-003-0945ND
2014-12-109588-012-0924ND
2015-01-273761-800-09356.50 ppb
2015-01-273761-801-09007.40 ppb
2015-01-273761-802-09505.00 ppb
2015-01-273761-803-0920ND
2015-01-273761-804-10359.60 ppb
2015-01-273761-805-1015ND
2015-01-273761-806-1000ND
2015-01-273761-807-1100ND
2015-03-259588-002-0953ND
2015-03-259588-003-0940ND
2015-03-259588-012-0926ND
2015-04-239588-002-1041ND
2015-04-239588-003-1024ND
2015-04-239588-012-0947ND
2015-05-053761-800-09156.30 ppb
2015-05-053761-801-082013.1 ppb
2015-05-053761-802-09057.20 ppb
2015-05-053761-803-0840ND
2015-05-053761-804-100512.6 ppb
2015-05-053761-805-09451.40 ppb
2015-05-053761-806-0930ND
2015-05-053761-807-0850ND
2015-07-309588-002-1044ND
2015-07-309588-003-1015ND
2015-07-309588-012-0928ND
2015-08-113761-800-09105.20 ppb
2015-08-113761-801-080010.6 ppb
2015-08-113761-802-08555.30 ppb
2015-08-113761-803-0826ND
2015-08-113761-804-095012.4 ppb
2015-08-113761-805-09351.40 ppb
2015-08-113761-806-0926ND
2015-08-113761-807-0840ND
2015-10-289588-002-1000ND
2015-10-289588-003-0945ND
2015-10-289588-012-0915ND
2015-11-033761-800-10303.30 ppb
2015-11-033761-801-08153.40 ppb
2015-11-033761-802-10183.20 ppb
2015-11-033761-803-0850ND
2015-11-033761-804-10004.20 ppb
2015-11-033761-805-0940ND
2015-11-033761-806-0920ND
2015-11-033761-807-0830ND
2016-02-023761-800-08453.90 ppb
2016-02-023761-801-07555.10 ppb
2016-02-023761-802-08303.90 ppb
2016-02-023761-803-0810ND
2016-02-023761-804-09405.10 ppb
2016-02-023761-805-0920ND
2016-02-023761-806-0900ND
2016-02-023761-807-1000ND
2016-03-249588-002-1024ND
2016-03-249588-003-1010ND
2016-03-249588-012-0940ND
2016-05-033761-800-11004.20 ppb
2016-05-033761-801-09214.40 ppb
2016-05-033761-802-10453.70 ppb
2016-05-033761-803-1010ND
2016-05-033761-804-12484.40 ppb
2016-05-033761-805-1230ND
2016-05-033761-806-1121ND
2016-05-033761-807-1027ND
2016-06-099588-002-0945ND
2016-06-099588-003-0923ND
2016-06-099588-012-0909ND
2016-07-209588-002-1015ND
2016-07-209588-003-0945ND
2016-07-209588-012-0915ND
2016-08-023761-800-083510.00 ppb
2016-08-023761-801-082011.9 ppb
2016-08-023761-802-085012.4 ppb
2016-08-023761-803-0750ND
2016-08-023761-804-10054.90 ppb
2016-08-023761-805-0945ND
2016-08-023761-806-09201.30 ppb
2016-08-023761-807-0805ND
2016-10-129588-002-0957ND
2016-10-129588-003-0928ND
2016-10-129588-012-0914ND
2016-11-013761-800-09005.70 ppb
2016-11-013761-801-08058.00 ppb
2016-11-013761-802-09156.50 ppb
2016-11-013761-803-0830ND
2016-11-013761-804-10305.70 ppb
2016-11-013761-805-1000ND
2016-11-013761-806-0935ND
2016-11-013761-807-0845ND
2017-01-189588-002-0935ND
2017-01-189588-003-0920ND
2017-01-189588-012-0900ND
2017-02-143761-800-09003.80 ppb
2017-02-143761-801-08054.00 ppb
2017-02-143761-802-09203.80 ppb
2017-02-143761-803-0845ND
2017-02-143761-804-10252.80 ppb
2017-02-143761-805-1005ND
2017-02-143761-806-0940ND
2017-02-143761-807-0825ND
2017-04-179588-002-0930ND
2017-04-179588-003-0952ND
2017-04-179588-012-0910ND
2017-05-093761-800-091021.8 ppb
2017-05-093761-801-07409.10 ppb
2017-05-093761-802-114024.0 ppb
2017-05-093761-803-0810ND
2017-05-093761-804-111819.3 ppb
2017-05-093761-805-1050ND
2017-05-093761-806-0925ND
2017-05-093761-807-0845ND
2017-07-249588-002-1028ND
2017-07-249588-003-0955ND
2017-07-249588-012-0923ND
2017-08-083761-800-09001.90 ppb
2017-08-083761-801-08001.80 ppb
2017-08-083761-802-09201.60 ppb
2017-08-083761-803-0840ND
2017-08-083761-804-09352.10 ppb
2017-08-083761-805-1000ND
2017-08-083761-806-10251.60 ppb
2017-08-083761-807-0830ND
2017-10-189588-002-0950ND
2017-10-189588-003-0940ND
2017-10-189588-012-0914ND
2017-11-143761-800-08254.90 ppb
2017-11-143761-801-07305.00 ppb
2017-11-143761-802-09003.90 ppb
2017-11-143761-803-0810ND
2017-11-143761-804-10005.60 ppb
2017-11-143761-805-0940ND
2017-11-143761-806-0920ND
2017-11-143761-807-0750ND
2018-01-249588-002-0940ND
2018-01-249588-003-0920ND
2018-02-063761-800-09353.00 ppb
2018-02-063761-801-08403.10 ppb
2018-02-063761-802-09502.10 ppb
2018-02-063761-803-0915ND
2018-02-063761-804-10502.70 ppb
2018-02-063761-805-1030ND
2018-02-063761-806-1010ND
2018-02-063761-807-0900ND
2018-04-119588-002-0953ND
2018-04-119588-003-0930ND
2018-05-013761-800-10264.80 ppb
2018-05-013761-801-10055.30 ppb
2018-05-013761-802-10374.00 ppb
2018-05-013761-803-1350ND
2018-05-013761-804-13004.50 ppb
2018-05-013761-805-1245ND
2018-05-013761-806-1117ND
2018-05-013761-807-1410ND
2018-07-259588-002-1000ND
2018-07-259588-003-0935ND
2018-08-073761-800-10235.80 ppb
2018-08-073761-801-08426.10 ppb
2018-08-073761-802-12456.40 ppb
2018-08-073761-803-0936ND
2018-08-073761-804-12256.00 ppb
2018-08-073761-805-1200ND
2018-08-073761-806-10481.10 ppb
2018-08-073761-807-1310ND
2018-10-269588-002-0940ND
2018-10-269588-003-0920ND
2018-11-063761-800-09104.40 ppb
2018-11-063761-801-08005.10 ppb
2018-11-063761-802-08554.40 ppb
2018-11-063761-803-0835ND
2018-11-063761-804-10054.20 ppb
2018-11-063761-805-0947ND
2018-11-063761-806-09301.000 ppb
2018-11-063761-807-0820ND
2019-01-239588-002-0950ND
2019-01-239588-003-0920ND
2019-02-053761-800-09224.60 ppb
2019-02-053761-801-08306.50 ppb
2019-02-053761-802-09404.30 ppb
2019-02-053761-803-0910ND
2019-02-053761-804-10364.50 ppb
2019-02-053761-805-1021ND
2019-02-053761-806-1000ND
2019-02-053761-807-0856ND
2019-04-259588-002-1030ND
2019-04-259588-003-1005ND
2019-05-073761-800-083512.4 ppb
2019-05-073761-801-07308.00 ppb
2019-05-073761-802-08503.30 ppb
2019-05-073761-803-0755ND
2019-05-073761-804-09503.30 ppb
2019-05-073761-805-0932ND
2019-05-073761-806-0915ND
2019-05-073761-807-0810ND
2019-05-249588-012-0920ND
2019-07-259588-002-1035ND
2019-07-259588-003-1010ND
2019-07-259588-012-0930ND
2019-08-063761-800-08501.50 ppb
2019-08-063761-801-07541.50 ppb
2019-08-063761-802-09161.20 ppb
2019-08-063761-803-0833ND
2019-08-063761-804-10251.30 ppb
2019-08-063761-805-1000ND
2019-08-063761-806-0940ND
2019-08-063761-807-0820ND
2019-10-259588-002-1000ND
2019-10-259588-003-1040ND
2019-10-259588-012-0930ND
2019-11-053761-800-09303.60 ppb
2019-11-053761-801-08303.60 ppb
2019-11-053761-802-09453.60 ppb
2019-11-053761-803-0850ND
2019-11-053761-804-10554.10 ppb
2019-11-053761-805-1030ND
2019-11-053761-806-10051.10 ppb
2019-11-053761-807-0910ND