Menu

EWG's Tap Water Database — 2021 UPDATE

Donate

Chloroform

City of San Juan

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

 

108

Samples

0

Samples exceeding legal limit (MCL)

42

Samples exceeding
health guidelines

Testing results - average by year

 
YearAverage resultSamples takenDetectionsRange of results
20140.361 ppb186ND - 1.80 ppb
2015ND180ND
2016ND180ND
20170.444 ppb186ND - 1.60 ppb
20181.69 ppb1817ND - 2.70 ppb
20192.26 ppb1813ND - 11.9 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
2014-02-28AC45290ND
2014-02-28AC452951.80 ppb
2014-02-28AC45294ND
2014-02-28AC45257ND
2014-04-22AC51384ND
2014-04-22AC51386ND
2014-04-22AC51385ND
2014-04-22AC51376ND
2014-07-23AC606800.700 ppb
2014-07-23AC607040.700 ppb
2014-07-23AC607891.10 ppb
2014-07-23AC60790ND
2014-07-23AC607911.10 ppb
2014-07-23AC60792ND
2014-10-21AC701891.10 ppb
2014-10-21AC70186ND
2014-10-21AC70147ND
2014-10-21AC70190ND
2015-01-21AC77206ND
2015-01-21AC77207ND
2015-01-21AC77197ND
2015-01-21AC77205ND
2015-04-07AC87473ND
2015-04-07AC87445ND
2015-04-07AC87453ND
2015-04-07AC87454ND
2015-07-14AC99405ND
2015-07-14AC99429ND
2015-07-14AC99329ND
2015-07-14AC99336ND
2015-07-14AC99338ND
2015-07-14AC99328ND
2015-10-20AD11155ND
2015-10-20AD11163ND
2015-10-20AD11172ND
2015-10-20AD11170ND
2016-01-29AD21029ND
2016-01-29AD21012ND
2016-01-29AD21014ND
2016-01-29AD21023ND
2016-04-29AD34805ND
2016-04-29AD34806ND
2016-04-29AD34807ND
2016-04-29AD34809ND
2016-07-14AD44293ND
2016-07-14AD44283ND
2016-07-14AD44236ND
2016-07-14AD44232ND
2016-07-14AD44220ND
2016-07-14AD44219ND
2016-11-15AD57987ND
2016-11-15AD58004ND
2016-11-15AD58009ND
2016-11-15AD57983ND
2017-01-10AD63922ND
2017-01-10AD63921ND
2017-01-10AD639201.20 ppb
2017-01-10AD63919ND
2017-04-21AD80640ND
2017-04-21AD806421.50 ppb
2017-04-21AD80639ND
2017-04-21AD80637ND
2017-07-14AD895301.20 ppb
2017-07-14AD89528ND
2017-07-14AD89484ND
2017-07-14AD894801.40 ppb
2017-07-14AD894811.60 ppb
2017-07-14AD894771.10 ppb
2017-10-31AE02898ND
2017-10-31AE02916ND
2017-10-31AE02902ND
2017-10-31AE02920ND
2018-01-24AE101471.30 ppb
2018-01-24AE101461.50 ppb
2018-01-24AE101351.80 ppb
2018-01-24AE101501.40 ppb
2018-04-11AE220432.70 ppb
2018-04-11AE220491.90 ppb
2018-04-11AE220442.60 ppb
2018-04-11AE220481.80 ppb
2018-08-16AE373731.90 ppb
2018-08-16AE37385ND
2018-08-16AE373231.10 ppb
2018-08-16AE373302.00 ppb
2018-08-16AE373331.20 ppb
2018-08-16AE373291.20 ppb
2018-10-10AE430511.80 ppb
2018-10-10AE430551.50 ppb
2018-10-10AE430592.10 ppb
2018-10-10AE430522.60 ppb
2019-02-26AE559441.10 ppb
2019-02-26AE559421.30 ppb
2019-02-26AE559471.10 ppb
2019-02-26AE559481.20 ppb
2019-05-21AE673342.00 ppb
2019-05-21AE6733511.9 ppb
2019-05-21AE673455.70 ppb
2019-05-21AE673436.70 ppb
2019-09-04AE820713.50 ppb
2019-09-04AE82075ND
2019-09-04AE820211.10 ppb
2019-09-04AE820171.50 ppb
2019-09-04AE820121.70 ppb
2019-09-04AE820191.80 ppb
2019-11-07AE88872ND
2019-11-07AE88869ND
2019-11-07AE88874ND
2019-11-07AE88871ND