Menu

EWG's Tap Water Database — 2021 UPDATE

Donate

Chloroform

Regional Water Authority

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

 

352

Samples

0

Samples exceeding legal limit (MCL)

321

Samples exceeding
health guidelines

Testing results - average by year

 
YearAverage resultSamples takenDetectionsRange of results
201436.3 ppb5854ND - 77.2 ppb
201526.0 ppb5954ND - 56.4 ppb
201633.7 ppb5853ND - 93.1 ppb
201733.6 ppb6054ND - 82.4 ppb
201842.9 ppb5853ND - 72.6 ppb
201928.2 ppb5953ND - 55.6 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
2014-03-04DBP 20039195429.6 ppb
2014-03-04DBP 20039195932.7 ppb
2014-03-04DBP 20039197437.9 ppb
2014-03-04VOC1 2003919636.20 ppb
2014-03-04VOC1 20039196410.7 ppb
2014-03-04VOC1 2003919651.70 ppb
2014-03-04VOC1 2003919772.20 ppb
2014-03-04VOC1 200391978ND
2014-03-04VOC1 200391979ND
2014-03-04VOC1 2003919808.60 ppb
2014-03-04VOC1 2003920050.700 ppb
2014-03-04VOC1 200392007ND
2014-03-05DBP 20039209242.8 ppb
2014-03-05DBP 20039209348.6 ppb
2014-03-05DBP 20039209428.9 ppb
2014-03-06DBP 20039215220.9 ppb
2014-03-06DBP 20039220146.1 ppb
2014-03-06DBP 20039220240.0 ppb
2014-03-07DBP 20039230633.8 ppb
2014-03-07DBP 20039230757.3 ppb
2014-03-07DBP 20039230846.2 ppb
2014-03-25VOC1 200393100ND
2014-06-02DBP 20039694859.9 ppb
2014-06-02DBP 20039694955.0 ppb
2014-06-02DBP 20039695036.6 ppb
2014-06-03DBP 20039695931.0 ppb
2014-06-03DBP 20039696431.9 ppb
2014-06-03DBP 20039698234.3 ppb
2014-06-03DBP 20039707343.4 ppb
2014-06-05DBP 20039722934.2 ppb
2014-06-05DBP 20039732750.6 ppb
2014-06-05DBP 20039732877.2 ppb
2014-06-06DBP 20039735473.2 ppb
2014-06-06DBP 20039735563.1 ppb
2014-09-02DBP 20040327237.5 ppb
2014-09-02DBP 20040327738.7 ppb
2014-09-02DBP 20040330239.6 ppb
2014-09-03DBP 20040347048.1 ppb
2014-09-03DBP 20040347136.0 ppb
2014-09-03DBP 20040347235.8 ppb
2014-09-04DBP 20040351755.2 ppb
2014-09-04DBP 20040355642.3 ppb
2014-09-04DBP 20040355749.4 ppb
2014-09-04DBP 20040355852.0 ppb
2014-09-06DBP 20040368749.8 ppb
2014-09-06DBP 20040368833.6 ppb
2014-12-02DBP 20040868327.8 ppb
2014-12-02DBP 20040868831.9 ppb
2014-12-02DBP 20040870638.4 ppb
2014-12-02DBP 20040874849.2 ppb
2014-12-02DBP 20040874956.8 ppb
2014-12-02DBP 20040875025.6 ppb
2014-12-03DBP 20040885637.0 ppb
2014-12-03DBP 20040885773.8 ppb
2014-12-04DBP 20040894631.1 ppb
2014-12-04DBP 20040896842.2 ppb
2014-12-04DBP 20040896948.1 ppb
2014-12-04DBP 20040897039.9 ppb
2015-03-02DBP 20041285025.5 ppb
2015-03-02DBP 20041285129.8 ppb
2015-03-03DBP 20041287022.4 ppb
2015-03-03DBP 20041286319.9 ppb
2015-03-03DBP 20041292925.2 ppb
2015-03-03DBP 20041292826.5 ppb
2015-03-03DBP 20041288338.6 ppb
2015-03-03VOC1 200412899ND
2015-03-03VOC1 200412902ND
2015-03-03VOC1 200412900ND
2015-03-03VOC1 2004128795.80 ppb
2015-03-03VOC1 20041288115.8 ppb
2015-03-03VOC1 2004129076.30 ppb
2015-03-03VOC1 2004129230.500 ppb
2015-03-04DBP 20041305127.7 ppb
2015-03-04VOC1 2004130221.60 ppb
2015-03-05DBP 20041315428.8 ppb
2015-03-05DBP 20041315631.4 ppb
2015-03-05DBP 20041315531.0 ppb
2015-03-05DBP 20041313027.1 ppb
2015-03-10VOC1 200413328ND
2015-03-18VOC1 2004137136.30 ppb
2015-06-01DBP 20041759532.3 ppb
2015-06-01DBP 20041756328.7 ppb
2015-06-01DBP 20041760324.6 ppb
2015-06-01DBP 20041760533.0 ppb
2015-06-01DBP 20041760230.1 ppb
2015-06-01DBP 20041760431.6 ppb
2015-06-02DBP 20041762925.4 ppb
2015-06-02DBP 20041762421.3 ppb
2015-06-02DBP 20041770129.5 ppb
2015-06-02DBP 20041769928.8 ppb
2015-06-03DBP 20041781925.4 ppb
2015-06-03DBP 20041782331.8 ppb
2015-09-01DBP 20042386640.0 ppb
2015-09-01DBP 20042386830.5 ppb
2015-09-01DBP 20042382146.4 ppb
2015-09-01DBP 20042381223.9 ppb
2015-09-01DBP 20042386942.0 ppb
2015-09-01DBP 20042386744.8 ppb
2015-09-01DBP 20042382929.7 ppb
2015-09-01DBP 20042380724.5 ppb
2015-09-02DBP 20042408233.4 ppb
2015-09-02DBP 20042408032.3 ppb
2015-09-02DBP 20042408138.5 ppb
2015-09-04DBP 20042427156.4 ppb
2015-12-01DBP 20042960245.0 ppb
2015-12-01DBP 20042954118.2 ppb
2015-12-01DBP 20042955625.8 ppb
2015-12-01DBP 20042954624.8 ppb
2015-12-01DBP 20042960425.0 ppb
2015-12-01DBP 20042960141.6 ppb
2015-12-02DBP 20042972530.0 ppb
2015-12-02DBP 20042975235.8 ppb
2015-12-02DBP 20042975134.5 ppb
2015-12-03DBP 20042987731.3 ppb
2015-12-03DBP 20042987525.0 ppb
2015-12-03DBP 20042987641.0 ppb
2015-12-04VOC1 200429711ND
2016-02-29VOC1 2004343865.10 ppb
2016-02-29VOC1 20043438720.2 ppb
2016-02-29VOC1 2004343719.70 ppb
2016-02-29VOC1 2004343722.10 ppb
2016-03-01DBP 20043442021.6 ppb
2016-03-01DBP 20043443215.9 ppb
2016-03-01DBP 20043443920.4 ppb
2016-03-01DBP 20043451828.4 ppb
2016-03-01VOC1 200434428ND
2016-03-01VOC1 200434431ND
2016-03-01VOC1 200434429ND
2016-03-01VOC1 200434430ND
2016-03-01VOC1 2004344740.800 ppb
2016-03-02DBP 20043465223.9 ppb
2016-03-02DBP 20043465333.3 ppb
2016-03-03DBP 20043470532.3 ppb
2016-03-03DBP 20043473436.7 ppb
2016-03-03DBP 20043479024.0 ppb
2016-03-03DBP 20043479129.2 ppb
2016-03-03VOC1 200434800ND
2016-03-04DBP 20043481930.7 ppb
2016-03-04DBP 20043482028.5 ppb
2016-06-01DBP 20044102529.3 ppb
2016-06-01DBP 20044102632.1 ppb
2016-06-01DBP 20044103737.1 ppb
2016-06-01DBP 20044105455.7 ppb
2016-06-01DBP 20044105547.8 ppb
2016-06-01DBP 20044105624.4 ppb
2016-06-01DBP 20044105751.1 ppb
2016-06-01DBP 20044105833.1 ppb
2016-06-02DBP 20044126238.3 ppb
2016-06-02DBP 20044129744.6 ppb
2016-06-02DBP 20044129850.9 ppb
2016-06-02DBP 20044129933.7 ppb
2016-09-06DBP 20044896946.8 ppb
2016-09-06DBP 20044897449.0 ppb
2016-09-06DBP 20044900159.5 ppb
2016-09-06DBP 20044901447.1 ppb
2016-09-06DBP 20044901566.4 ppb
2016-09-06DBP 20044901671.0 ppb
2016-09-07DBP 20044921459.8 ppb
2016-09-08DBP 20044940771.5 ppb
2016-09-08DBP 20044940867.1 ppb
2016-09-09DBP 20044950050.3 ppb
2016-09-12DBP 20044954564.7 ppb
2016-09-12DBP 20044954793.1 ppb
2016-12-05DBP 20045608126.3 ppb
2016-12-05DBP 20045608337.1 ppb
2016-12-06DBP 20045608840.9 ppb
2016-12-06DBP 20045611027.5 ppb
2016-12-06DBP 20045611530.1 ppb
2016-12-06DBP 20045617539.4 ppb
2016-12-07DBP 2004563588.90 ppb
2016-12-07DBP 20045635938.9 ppb
2016-12-08DBP 2004564531.30 ppb
2016-12-08DBP 20045646053.6 ppb
2016-12-08DBP 20045646138.2 ppb
2016-12-08DBP 20045646225.9 ppb
2017-02-27VOC1 2004613168.60 ppb
2017-02-27VOC1 2004613172.80 ppb
2017-02-27VOC1 2004613017.40 ppb
2017-02-28VOC1 200461369ND
2017-02-28VOC1 200461372ND
2017-02-28VOC1 200461370ND
2017-02-28VOC1 200461371ND
2017-02-28VOC1 2004614051.30 ppb
2017-02-28VOC1 2004614071.000 ppb
2017-03-01DBP 20046149628.9 ppb
2017-03-01DBP 20046154229.1 ppb
2017-03-01DBP 20046154335.5 ppb
2017-03-01DBP 20046154427.4 ppb
2017-03-01DBP 20046154535.7 ppb
2017-03-01DBP 20046154630.7 ppb
2017-03-02DBP 20046165026.0 ppb
2017-03-02DBP 20046165127.0 ppb
2017-03-02DBP 20046167349.6 ppb
2017-03-02DBP 20046167441.9 ppb
2017-03-02DBP 2004616759.30 ppb
2017-03-02VOC1 200461633ND
2017-03-03DBP 2004617276.70 ppb
2017-06-05DBP 20046842031.7 ppb
2017-06-05DBP 20046842141.7 ppb
2017-06-06DBP 20046847629.0 ppb
2017-06-06DBP 20046848131.2 ppb
2017-06-06DBP 20046850043.0 ppb
2017-06-07DBP 20046866926.8 ppb
2017-06-07DBP 20046867043.4 ppb
2017-06-08DBP 20046885018.7 ppb
2017-06-08DBP 20046894650.9 ppb
2017-06-08DBP 20046894753.1 ppb
2017-06-08DBP 20046894838.8 ppb
2017-06-08DBP 20046894933.1 ppb
2017-06-19VOC1 2004696871.40 ppb
2017-06-19VOC1 200469688ND
2017-09-05DBP 20047578542.9 ppb
2017-09-05DBP 20047579044.6 ppb
2017-09-05DBP 20047580059.0 ppb
2017-09-07DBP 20047610442.7 ppb
2017-09-07DBP 20047622076.0 ppb
2017-09-07DBP 20047622156.8 ppb
2017-09-07DBP 20047622267.1 ppb
2017-09-07DBP 20047622468.9 ppb
2017-09-08DBP 20047630275.2 ppb
2017-09-08DBP 20047630482.4 ppb
2017-09-08DBP 20047630547.3 ppb
2017-09-08DBP 20047630644.5 ppb
2017-12-05DBP 20048337630.1 ppb
2017-12-05DBP 20048338133.8 ppb
2017-12-05DBP 20048339147.7 ppb
2017-12-07DBP 20048377044.4 ppb
2017-12-07DBP 20048377150.7 ppb
2017-12-07DBP 20048377241.8 ppb
2017-12-07DBP 20048377335.9 ppb
2017-12-07DBP 20048377449.8 ppb
2017-12-08DBP 20048383427.3 ppb
2017-12-08DBP 20048384346.0 ppb
2017-12-08DBP 20048384446.8 ppb
2017-12-08DBP 20048384540.5 ppb
2018-03-05VOC1 200489156ND
2018-03-05VOC1 20048912813.7 ppb
2018-03-05VOC1 20048912919.0 ppb
2018-03-05VOC1 2004891509.00 ppb
2018-03-06DBP 20048926842.1 ppb
2018-03-06DBP 20048927543.7 ppb
2018-03-06DBP 20048928754.1 ppb
2018-03-06VOC1 200489295ND
2018-03-06VOC1 200489298ND
2018-03-06VOC1 200489296ND
2018-03-07DBP 20048953743.4 ppb
2018-03-07DBP 20048953852.3 ppb
2018-03-07DBP 20048953972.6 ppb
2018-03-07DBP 20048954057.8 ppb
2018-03-07DBP 20048954141.8 ppb
2018-03-08DBP 20048956530.6 ppb
2018-03-09DBP 20048970167.5 ppb
2018-03-09DBP 20048970270.9 ppb
2018-03-09DBP 20048970335.5 ppb
2018-06-05DBP 20049598443.0 ppb
2018-06-05DBP 20049598946.1 ppb
2018-06-05DBP 20049600258.3 ppb
2018-06-06DBP 20049623553.2 ppb
2018-06-07DBP 20049637535.4 ppb
2018-06-07DBP 20049637649.4 ppb
2018-06-07DBP 20049641737.4 ppb
2018-06-08DBP 20049650762.1 ppb
2018-06-08DBP 20049650839.5 ppb
2018-06-08DBP 20049650959.7 ppb
2018-06-08DBP 20049651059.4 ppb
2018-06-08DBP 20049651141.8 ppb
2018-08-17VOC1 20050273517.6 ppb
2018-09-04DBP 20050373252.6 ppb
2018-09-04DBP 20050373753.8 ppb
2018-09-04DBP 20050384259.8 ppb
2018-09-04DBP 20050391270.8 ppb
2018-09-04DBP 20050391371.0 ppb
2018-09-04DBP 20050391454.8 ppb
2018-09-05DBP 20050398166.7 ppb
2018-09-05DBP 20050408642.7 ppb
2018-09-05DBP 20050408743.9 ppb
2018-09-06DBP 20050418542.1 ppb
2018-09-06DBP 20050421157.2 ppb
2018-09-07DBP 20050444147.0 ppb
2018-11-29VOC1 200514106ND
2018-11-29VOC1 2005141211.000 ppb
2018-12-03DBP 20051437227.2 ppb
2018-12-03DBP 20051440641.8 ppb
2018-12-04DBP 20051444741.9 ppb
2018-12-04DBP 20051445249.8 ppb
2018-12-04DBP 20051462561.6 ppb
2018-12-04DBP 20051462665.5 ppb
2018-12-04DBP 20051462749.3 ppb
2018-12-04DBP 20051462839.4 ppb
2018-12-04DBP 20051462950.7 ppb
2018-12-05DBP 20051495251.3 ppb
2018-12-06DBP 20051506941.0 ppb
2018-12-06DBP 20051507049.8 ppb
2019-03-04DBP 20052321520.8 ppb
2019-03-04DBP 20052321726.6 ppb
2019-03-04VOC1 2005231506.60 ppb
2019-03-04VOC1 2005231516.80 ppb
2019-03-04VOC1 2005231756.90 ppb
2019-03-04VOC1 2005231761.20 ppb
2019-03-05DBP 20052326222.0 ppb
2019-03-05DBP 20052326925.5 ppb
2019-03-05DBP 20052345626.2 ppb
2019-03-05DBP 20052345736.4 ppb
2019-03-05DBP 20052345827.9 ppb
2019-03-05DBP 20052345924.8 ppb
2019-03-05DBP 20052346317.9 ppb
2019-03-05VOC1 200523251ND
2019-03-05VOC1 200523254ND
2019-03-05VOC1 200523252ND
2019-03-05VOC1 200523253ND
2019-03-05VOC1 2005232840.600 ppb
2019-03-05VOC1 200523286ND
2019-03-07DBP 20052388423.2 ppb
2019-03-08DBP 20052400019.9 ppb
2019-03-08DBP 20052400227.0 ppb
2019-05-08VOC1 200531298ND
2019-06-03DBP 20053437334.9 ppb
2019-06-03DBP 20053441437.1 ppb
2019-06-04DBP 20053449133.3 ppb
2019-06-04DBP 20053449635.3 ppb
2019-06-04DBP 20053460032.2 ppb
2019-06-04DBP 20053472541.3 ppb
2019-06-04DBP 20053472737.4 ppb
2019-06-04DBP 20053472944.4 ppb
2019-06-05DBP 20053503948.4 ppb
2019-06-05DBP 20053504134.7 ppb
2019-06-06DBP 20053519736.6 ppb
2019-06-07DBP 20053535741.4 ppb
2019-09-03DBP 20054698839.7 ppb
2019-09-03DBP 20054699345.9 ppb
2019-09-04DBP 20054740036.3 ppb
2019-09-04DBP 20054740247.1 ppb
2019-09-04DBP 20054740346.8 ppb
2019-09-04DBP 20054740441.7 ppb
2019-09-04DBP 20054740536.9 ppb
2019-09-05DBP 20054746050.7 ppb
2019-09-05DBP 20054766755.6 ppb
2019-09-06DBP 20054782642.4 ppb
2019-09-06DBP 20054782750.7 ppb
2019-09-06DBP 20054782841.4 ppb
2019-12-02DBP 20055840535.3 ppb
2019-12-02DBP 20055840628.8 ppb
2019-12-02DBP 20055840737.0 ppb
2019-12-03DBP 20055845425.9 ppb
2019-12-03DBP 20055845930.5 ppb
2019-12-03DBP 20055861230.6 ppb
2019-12-04DBP 20055891627.6 ppb
2019-12-04DBP 20055891730.1 ppb
2019-12-04DBP 20055891920.8 ppb
2019-12-05DBP 20055907332.5 ppb
2019-12-05DBP 20055909823.2 ppb
2019-12-06DBP 20055919528.6 ppb