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EWG's Tap Water Database — 2021 UPDATE

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Chloroform

San Antonio Water System Northeast

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

 

117

Samples

0

Samples exceeding legal limit (MCL)

69

Samples exceeding
health guidelines

Testing results - average by year

 
YearAverage resultSamples takenDetectionsRange of results
2013N/A00N/A
20143.71 ppb1714ND - 7.40 ppb
20155.15 ppb2019ND - 12.0 ppb
20160.194 ppb163ND - 1.10 ppb
20170.278 ppb184ND - 1.40 ppb
20183.49 ppb2012ND - 13.1 ppb
20193.02 ppb2617ND - 13.9 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
2014-02-14AC431005.00 ppb
2014-02-14AC431066.40 ppb
2014-02-14AC430445.00 ppb
2014-02-14AC430484.70 ppb
2014-04-02AC491245.30 ppb
2014-04-02AC490957.40 ppb
2014-04-02AC490856.50 ppb
2014-04-02AC491066.00 ppb
2014-07-02AC587672.30 ppb
2014-07-02AC587643.40 ppb
2014-07-02AC587743.40 ppb
2014-07-02AC587751.80 ppb
2014-09-02AC654512.80 ppb
2014-10-02AC68793ND
2014-10-02AC687943.10 ppb
2014-10-02AC68790ND
2014-10-02AC68767ND
2015-01-15AC76420ND
2015-01-15AC764441.000 ppb
2015-01-15AC764431.000 ppb
2015-01-15AC764291.000 ppb
2015-05-01AC902343.30 ppb
2015-05-01AC902543.60 ppb
2015-05-01AC902482.50 ppb
2015-05-01AC902493.80 ppb
2015-07-08AC987496.50 ppb
2015-07-08AC987539.40 ppb
2015-07-08AC987476.80 ppb
2015-07-08AC987062.50 ppb
2015-07-08AC987107.50 ppb
2015-07-08AC987097.90 ppb
2015-07-08AC987086.90 ppb
2015-07-09AC989963.60 ppb
2015-10-14AD105985.30 ppb
2015-10-14AD1059112.0 ppb
2015-10-14AD105869.30 ppb
2015-10-14AD105999.10 ppb
2016-01-12AD17559ND
2016-01-12AD175631.000 ppb
2016-01-12AD17533ND
2016-01-12AD17532ND
2016-04-04AD31635ND
2016-04-04AD316391.000 ppb
2016-04-04AD31634ND
2016-04-04AD31636ND
2016-07-20AD44880ND
2016-07-20AD44875ND
2016-07-20AD44870ND
2016-07-20AD44878ND
2016-10-12AD53118ND
2016-10-12AD53120ND
2016-10-12AD531191.10 ppb
2016-10-12AD53135ND
2017-01-05AD63192ND
2017-01-05AD63196ND
2017-01-05AD63190ND
2017-01-05AD63193ND
2017-04-03AD78036ND
2017-04-03AD78034ND
2017-04-03AD78037ND
2017-04-03AD780391.20 ppb
2017-07-07AD88653ND
2017-07-07AD88636ND
2017-07-07AD886371.30 ppb
2017-07-07AD886301.10 ppb
2017-12-04AE06545ND
2017-12-04AE06537ND
2017-12-04AE065421.40 ppb
2017-12-04AE06543ND
2017-12-04AE06578ND
2017-12-13AE07674ND
2018-01-18AE09212ND
2018-01-18AE09213ND
2018-01-18AE09223ND
2018-01-18AE09220ND
2018-03-15AE18626ND
2018-03-26AE19964ND
2018-04-19AE231952.80 ppb
2018-04-19AE23204ND
2018-04-19AE231994.40 ppb
2018-04-19AE231961.60 ppb
2018-05-10AE259652.20 ppb
2018-05-10AE25967ND
2018-08-31AE391303.30 ppb
2018-08-31AE391286.60 ppb
2018-08-31AE391313.80 ppb
2018-08-31AE391295.90 ppb
2018-11-20AE466525.50 ppb
2018-11-20AE4665511.0 ppb
2018-11-20AE466549.50 ppb
2018-11-20AE4665313.1 ppb
2019-01-28AE515919.40 ppb
2019-01-28AE5159012.0 ppb
2019-01-28AE5158810.3 ppb
2019-01-28AE5158913.9 ppb
2019-04-22AE632133.80 ppb
2019-04-22AE632051.000 ppb
2019-04-22AE631462.90 ppb
2019-04-22AE631484.10 ppb
2019-04-22AE631473.70 ppb
2019-04-22AE631494.30 ppb
2019-07-26AE76121ND
2019-07-26AE761241.80 ppb
2019-07-26AE76126ND
2019-07-26AE76122ND
2019-07-26AE761202.80 ppb
2019-07-26AE761231.20 ppb
2019-07-26AE761252.90 ppb
2019-07-26AE761632.40 ppb
2019-10-29AE87840ND
2019-10-29AE87846ND
2019-10-29AE87855ND
2019-10-29AE87843ND
2019-10-29AE87861ND
2019-10-29AE87842ND
2019-10-29AE878441.000 ppb
2019-10-29AE878451.10 ppb