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EWG's Tap Water Database — 2021 UPDATE

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Chloroform

Western Municipal Water District

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

 

168

Samples

0

Samples exceeding legal limit (MCL)

126

Samples exceeding
health guidelines

Testing results - average by year

 
YearAverage resultSamples takenDetectionsRange of results
2013N/A00N/A
20141.33 ppb881.20 ppb - 1.40 ppb
20151.27 ppb4031ND - 3.30 ppb
20161.46 ppb3220ND - 4.90 ppb
20177.30 ppb2418ND - 18.0 ppb
20182.04 ppb3225ND - 4.30 ppb
20194.55 ppb3224ND - 19.0 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
2014-08-064790-011-14201.40 ppb
2014-08-064790-012-12451.20 ppb
2014-08-064790-013-15301.40 ppb
2014-08-064790-014-11451.40 ppb
2014-08-064790-015-13451.30 ppb
2014-08-064790-016-10401.30 ppb
2014-08-064790-017-09351.20 ppb
2014-08-064790-018-10101.40 ppb
2015-02-044790-011-0905ND
2015-02-044790-012-10201.80 ppb
2015-02-044790-013-14502.00 ppb
2015-02-044790-014-11002.00 ppb
2015-02-044790-015-09300.870 ppb
2015-02-044790-016-13101.60 ppb
2015-02-044790-017-12350.730 ppb
2015-02-044790-018-13501.60 ppb
2015-03-054790-011-11150.510 ppb
2015-03-054790-012-09301.60 ppb
2015-03-054790-013-14101.40 ppb
2015-03-054790-014-10151.50 ppb
2015-03-054790-015-1055ND
2015-03-054790-016-13351.30 ppb
2015-03-054790-017-11500.840 ppb
2015-03-054790-018-13201.30 ppb
2015-05-064790-011-1245ND
2015-05-064790-012-11001.30 ppb
2015-05-064790-013-13451.80 ppb
2015-05-064790-014-11401.40 ppb
2015-05-064790-015-1220ND
2015-05-064790-016-13151.40 ppb
2015-05-064790-017-09500.640 ppb
2015-05-064790-018-10151.30 ppb
2015-08-064790-011-1435ND
2015-08-064790-012-12552.60 ppb
2015-08-064790-013-15153.30 ppb
2015-08-064790-014-13452.90 ppb
2015-08-064790-015-1415ND
2015-08-064790-016-10252.50 ppb
2015-08-064790-017-10553.30 ppb
2015-08-064790-018-09552.60 ppb
2015-11-054790-011-1050ND
2015-11-054790-012-09451.40 ppb
2015-11-054790-013-12301.80 ppb
2015-11-054790-014-09001.50 ppb
2015-11-054790-015-1030ND
2015-11-054790-016-11150.940 ppb
2015-11-054790-017-1200ND
2015-11-054790-018-11300.920 ppb
2016-02-024790-011-1100ND
2016-02-024790-012-09000.700 ppb
2016-02-024790-013-14400.650 ppb
2016-02-024790-014-09400.610 ppb
2016-02-024790-015-1030ND
2016-02-024790-016-1415ND
2016-02-024790-017-1340ND
2016-02-024790-018-1400ND
2016-05-044790-011-0850ND
2016-05-044790-012-08153.70 ppb
2016-05-044790-013-11204.90 ppb
2016-05-044790-014-07304.00 ppb
2016-05-044790-015-0910ND
2016-05-044790-016-09351.60 ppb
2016-05-044790-017-10400.770 ppb
2016-05-044790-018-10001.80 ppb
2016-08-034790-011-1155ND
2016-08-034790-012-10502.70 ppb
2016-08-034790-013-14303.80 ppb
2016-08-034790-014-09303.10 ppb
2016-08-034790-015-1130ND
2016-08-034790-016-13403.80 ppb
2016-08-034790-017-12403.00 ppb
2016-08-034790-018-13153.50 ppb
2016-11-034790-011-1520ND
2016-11-034790-012-14002.10 ppb
2016-11-034790-013-09502.00 ppb
2016-11-034790-014-14302.00 ppb
2016-11-034790-015-1500ND
2016-11-034790-016-10501.000 ppb
2016-11-034790-017-1140ND
2016-11-034790-018-11151.000 ppb
2017-05-044790-011-0820ND
2017-05-044790-012-104013.0 ppb
2017-05-044790-013-133016.0 ppb
2017-05-044790-014-095513.0 ppb
2017-05-044790-015-0855ND
2017-05-044790-016-125013.0 ppb
2017-05-044790-017-120013.0 ppb
2017-05-044790-018-123013.0 ppb
2017-08-024790-011-0850ND
2017-08-024790-012-104012.0 ppb
2017-08-024790-013-134018.0 ppb
2017-08-024790-014-095512.0 ppb
2017-08-024790-015-0915ND
2017-08-024790-016-124016.0 ppb
2017-08-024790-017-11151.60 ppb
2017-08-024790-018-120512.0 ppb
2017-11-014790-011-0810ND
2017-11-014790-012-10103.30 ppb
2017-11-014790-013-12354.70 ppb
2017-11-014790-014-09253.40 ppb
2017-11-014790-015-0845ND
2017-11-014790-016-12103.70 ppb
2017-11-014790-017-11203.70 ppb
2017-11-014790-018-11453.80 ppb
2018-02-074790-011-0715ND
2018-02-074790-012-09103.00 ppb
2018-02-074790-013-12203.20 ppb
2018-02-074790-014-08303.10 ppb
2018-02-074790-015-0745ND
2018-02-074790-016-11101.80 ppb
2018-02-074790-017-10000.520 ppb
2018-02-074790-018-10402.00 ppb
2018-05-024790-011-0710ND
2018-05-024790-012-08552.80 ppb
2018-05-024790-013-11354.30 ppb
2018-05-024790-014-08152.70 ppb
2018-05-024790-015-0735ND
2018-05-024790-016-10503.30 ppb
2018-05-024790-017-10003.20 ppb
2018-05-024790-018-10303.60 ppb
2018-08-014790-011-08302.90 ppb
2018-08-014790-012-10202.50 ppb
2018-08-014790-013-12403.40 ppb
2018-08-014790-014-09303.00 ppb
2018-08-014790-015-08502.80 ppb
2018-08-014790-016-12002.40 ppb
2018-08-014790-017-11002.50 ppb
2018-08-014790-018-11402.40 ppb
2018-11-014790-011-0835ND
2018-11-014790-012-10202.10 ppb
2018-11-014790-013-14502.40 ppb
2018-11-014790-014-09352.20 ppb
2018-11-014790-015-0900ND
2018-11-014790-016-14251.50 ppb
2018-11-014790-017-1215ND
2018-11-014790-018-14101.50 ppb
2019-02-074790-011-0945ND
2019-02-074790-012-11453.30 ppb
2019-02-074790-013-1325ND
2019-02-074790-014-10352.90 ppb
2019-02-074790-015-1000ND
2019-02-074790-016-1300ND
2019-02-074790-017-1215ND
2019-02-074790-018-1240ND
2019-05-094790-011-08054.60 ppb
2019-05-094790-012-10104.00 ppb
2019-05-094790-013-14054.50 ppb
2019-05-094790-014-09153.40 ppb
2019-05-094790-015-08202.70 ppb
2019-05-094790-016-13054.00 ppb
2019-05-094790-017-11351.10 ppb
2019-05-094790-018-12504.10 ppb
2019-08-074790-011-08003.50 ppb
2019-08-074790-012-093010.00 ppb
2019-08-074790-013-135018.0 ppb
2019-08-074790-014-090015.0 ppb
2019-08-074790-015-08204.70 ppb
2019-08-074790-016-132013.0 ppb
2019-08-074790-017-113019.0 ppb
2019-08-074790-018-130512.0 ppb
2019-11-064790-011-1015ND
2019-11-064790-012-11402.90 ppb
2019-11-064790-013-13552.80 ppb
2019-11-064790-014-11052.60 ppb
2019-11-064790-015-1000ND
2019-11-064790-016-12452.60 ppb
2019-11-064790-017-12052.40 ppb
2019-11-064790-018-12302.60 ppb