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EWG's Tap Water Database — 2021 UPDATE

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Chloroform

Madison Water Utility

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

 

247

Samples

0

Samples exceeding legal limit (MCL)

73

Samples exceeding
health guidelines

Testing results - average by year

 
YearAverage resultSamples takenDetectionsRange of results
20140.510 ppb4921ND - 3.90 ppb
20150.559 ppb4420ND - 3.50 ppb
20160.499 ppb2912ND - 3.10 ppb
20170.595 ppb5121ND - 4.40 ppb
20180.407 ppb4122ND - 2.70 ppb
20190.522 ppb3313ND - 4.60 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
2014-01-21767449ND
2014-01-21767448ND
2014-01-217674520.460 ppb
2014-01-217674380.540 ppb
2014-01-22767447ND
2014-01-22767443ND
2014-01-22767445ND
2014-01-227674870.300 ppb
2014-01-227674881.10 ppb
2014-01-227674462.90 ppb
2014-01-297682100.300 ppb
2014-02-14770975ND
2014-02-17770977ND
2014-02-187709730.220 ppb
2014-02-187709741.20 ppb
2014-02-187709721.50 ppb
2014-04-037782960.280 ppb
2014-04-04778295ND
2014-04-07778297ND
2014-04-07778298ND
2014-04-227820910.930 ppb
2014-04-227820903.00 ppb
2014-04-23782084ND
2014-04-23782089ND
2014-04-23782085ND
2014-04-237820880.190 ppb
2014-04-237820870.230 ppb
2014-05-05784135ND
2014-05-057841311.000 ppb
2014-07-14803099ND
2014-07-14803096ND
2014-07-14803098ND
2014-07-14803097ND
2014-07-148031000.260 ppb
2014-07-15803105ND
2014-07-15803102ND
2014-07-15803101ND
2014-07-158031031.90 ppb
2014-07-158031043.90 ppb
2014-08-04808190ND
2014-08-04808191ND
2014-08-048081920.570 ppb
2014-10-14825834ND
2014-10-14825836ND
2014-10-14825835ND
2014-10-148258371.20 ppb
2014-10-148258383.00 ppb
2014-10-15825840ND
2014-10-15825839ND
2015-01-20839968ND
2015-01-20839967ND
2015-01-208399720.700 ppb
2015-01-208399712.40 ppb
2015-02-23844761ND
2015-02-23844760ND
2015-02-23844745ND
2015-02-23844741ND
2015-02-23844763ND
2015-02-23844742ND
2015-02-238447430.230 ppb
2015-02-238447440.240 ppb
2015-02-238447640.330 ppb
2015-02-238447403.40 ppb
2015-03-10847889ND
2015-04-21855404ND
2015-04-21855403ND
2015-04-21855408ND
2015-04-21855407ND
2015-04-21855402ND
2015-04-218554060.300 ppb
2015-04-218554100.880 ppb
2015-04-218554092.30 ppb
2015-05-05858198ND
2015-05-05858197ND
2015-07-21872306ND
2015-07-21872301ND
2015-07-21872309ND
2015-07-21872300ND
2015-07-218723100.210 ppb
2015-07-218722980.240 ppb
2015-07-218722960.750 ppb
2015-07-218723080.790 ppb
2015-07-218723040.790 ppb
2015-07-218722991.90 ppb
2015-07-218723023.00 ppb
2015-07-22872696ND
2015-07-22872695ND
2015-10-198900020.210 ppb
2015-10-20890005ND
2015-10-20890007ND
2015-10-208900030.320 ppb
2015-10-208899992.10 ppb
2015-10-208900003.50 ppb
2016-01-199021450.590 ppb
2016-01-199021461.20 ppb
2016-01-20902152ND
2016-01-20902149ND
2016-01-20902157ND
2016-01-20902151ND
2016-01-20902153ND
2016-01-20902150ND
2016-01-20902154ND
2016-04-19916893ND
2016-04-19916888ND
2016-04-19916894ND
2016-04-199168910.290 ppb
2016-04-199168920.880 ppb
2016-04-199168891.70 ppb
2016-07-19934715ND
2016-07-19934709ND
2016-07-19934717ND
2016-07-199347050.270 ppb
2016-07-199347141.70 ppb
2016-07-199347121.90 ppb
2016-07-20935007ND
2016-08-249416200.610 ppb
2016-10-18954229ND
2016-10-18954235ND
2016-10-18954232ND
2016-10-189542330.320 ppb
2016-10-189542271.90 ppb
2016-10-189542283.10 ppb
2017-01-18970480ND
2017-01-18970485ND
2017-01-18970477ND
2017-01-18970478ND
2017-01-189704840.410 ppb
2017-01-189704820.580 ppb
2017-01-189704830.590 ppb
2017-01-24970986ND
2017-01-24970991ND
2017-01-24970992ND
2017-01-24970988ND
2017-01-24970990ND
2017-01-249709840.680 ppb
2017-01-249709851.70 ppb
2017-01-249709874.40 ppb
2017-02-16974146ND
2017-04-18984277ND
2017-04-18984278ND
2017-04-18984283ND
2017-04-189842870.470 ppb
2017-04-189842881.50 ppb
2017-04-189842893.70 ppb
2017-04-19984286ND
2017-04-19984284ND
2017-04-19984285ND
2017-04-19984279ND
2017-04-19984276ND
2017-04-199842820.280 ppb
2017-04-199842900.320 ppb
2017-07-171004640ND
2017-07-171004639ND
2017-07-171004637ND
2017-07-1710046380.480 ppb
2017-07-181004645ND
2017-07-181004646ND
2017-07-181004642ND
2017-07-1810046410.300 ppb
2017-07-1810046430.700 ppb
2017-07-1810046440.740 ppb
2017-07-1810046841.70 ppb
2017-07-1810046853.50 ppb
2017-08-1410109391.10 ppb
2017-10-161024784ND
2017-10-161024785ND
2017-10-161024788ND
2017-10-161024787ND
2017-10-161024783ND
2017-10-1610247822.10 ppb
2017-10-1710247011.20 ppb
2017-10-1710247003.90 ppb
2017-12-191034398ND
2018-01-161037644ND
2018-01-161037645ND
2018-01-161037642ND
2018-01-161037643ND
2018-01-161037640ND
2018-01-161037647ND
2018-01-1610376381.50 ppb
2018-01-171037648ND
2018-01-1710376500.560 ppb
2018-01-1710376492.20 ppb
2018-03-1310449350.280 ppb
2018-04-1639178340.1000 ppb
2018-04-1639178390.1000 ppb
2018-04-1639178370.1000 ppb
2018-04-1739178380.1000 ppb
2018-04-1739178360.1000 ppb
2018-04-1739178350.200 ppb
2018-04-173914791-920.500 ppb
2018-04-173914789-901.90 ppb
2018-07-173992318ND
2018-07-173992319ND
2018-07-173992317ND
2018-07-173992316ND
2018-07-1739923150.1000 ppb
2018-07-1739923200.200 ppb
2018-07-1739923100.300 ppb
2018-07-173991853-540.900 ppb
2018-07-173991851-522.70 ppb
2018-08-0940180810.300 ppb
2018-09-111079446ND
2018-09-111079449ND
2018-09-1110794520.730 ppb
2018-10-164091676ND
2018-10-164091677ND
2018-10-164091678ND
2018-10-164091675ND
2018-10-164091548-491.10 ppb
2018-10-164091546-472.50 ppb
2018-10-174093738ND
2018-10-174093740ND
2018-10-1740937390.200 ppb
2019-01-161101627ND
2019-01-1611016230.310 ppb
2019-01-1611016930.840 ppb
2019-01-1611016922.50 ppb
2019-03-111109100ND
2019-03-111109102ND
2019-03-111109101ND
2019-03-111109103ND
2019-04-161115411ND
2019-04-161115486ND
2019-04-161115414ND
2019-04-161115492ND
2019-04-161115484ND
2019-04-1611154940.380 ppb
2019-04-1611155550.670 ppb
2019-04-1611155561.90 ppb
2019-07-151134797ND
2019-07-151134799ND
2019-07-151134798ND
2019-07-151134800ND
2019-07-151134801ND
2019-07-1611348030.450 ppb
2019-07-1611347610.570 ppb
2019-07-1611348020.910 ppb
2019-07-1611347604.60 ppb
2019-07-181135762ND
2019-10-141155272ND
2019-10-141155276ND
2019-10-141155275ND
2019-10-151155274ND
2019-10-1511552730.380 ppb
2019-10-1511552801.50 ppb
2019-10-1511552792.20 ppb