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EWG's Tap Water Database — 2021 UPDATE

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Chloroform

Bethesda WSC

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

 

171

Samples

0

Samples exceeding legal limit (MCL)

114

Samples exceeding
health guidelines

Testing results - average by year

 
YearAverage resultSamples takenDetectionsRange of results
2013N/A00N/A
20144.00 ppb2015ND - 10.4 ppb
20153.85 ppb3121ND - 16.4 ppb
20163.23 ppb3221ND - 10.4 ppb
20172.91 ppb3122ND - 5.34 ppb
20182.57 ppb3117ND - 9.95 ppb
20193.41 ppb2618ND - 6.97 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
2014-03-20Q14091140013.10 ppb
2014-03-20Q14091140022.30 ppb
2014-03-20Q14091140033.60 ppb
2014-03-20Q14091140042.80 ppb
2014-06-13Q14213280124.60 ppb
2014-06-13Q1421328013ND
2014-06-13Q14213280146.00 ppb
2014-06-13Q142132800110.1 ppb
2014-09-08Q14419540036.40 ppb
2014-09-08Q144195400410.4 ppb
2014-09-08Q14419540017.10 ppb
2014-09-08Q14419540029.80 ppb
2014-11-19Q14567300054.10 ppb
2014-11-19Q14567300062.90 ppb
2014-11-19Q14567300072.90 ppb
2014-11-19Q14567300083.90 ppb
2014-11-19Q1456730013ND
2014-11-19Q1456730015ND
2014-11-19Q1456730017ND
2014-11-19Q1456730019ND
2015-02-03Q1504044002ND
2015-02-03Q15040440062.20 ppb
2015-02-03Q1504044007ND
2015-02-03Q15040440081.90 ppb
2015-02-03Q15040440052.00 ppb
2015-04-22Q1515039035ND
2015-04-22Q1515039037ND
2015-04-22Q15150390403.81 ppb
2015-04-22Q1515039041ND
2015-04-22Q15150390434.60 ppb
2015-04-22Q15150390463.94 ppb
2015-04-22Q1515039025ND
2015-04-22Q15150390281.06 ppb
2015-04-22Q1515039030ND
2015-04-22Q1515039032ND
2015-04-22Q1515039034ND
2015-04-22Q15150390215.14 ppb
2015-04-22Q15150390224.92 ppb
2015-04-22Q15150390235.16 ppb
2015-04-22Q15150390245.77 ppb
2015-06-17Q1522842001ND
2015-08-04Q15302330015.62 ppb
2015-08-04Q15302330045.58 ppb
2015-08-04Q15302330075.96 ppb
2015-08-04Q15302330084.74 ppb
2015-08-04Q15302330096.72 ppb
2015-08-04Q15302330106.54 ppb
2015-11-02Q154343200116.4 ppb
2015-11-02Q15434320021.08 ppb
2015-11-02Q154343200313.4 ppb
2015-11-02Q154343200412.8 ppb
2016-02-17Q1607184002ND
2016-02-17Q16071840031.78 ppb
2016-02-17Q16071840083.40 ppb
2016-02-17Q1607184009ND
2016-02-17Q16071840103.07 ppb
2016-02-17Q16071840111.84 ppb
2016-03-21Q16113650041.74 ppb
2016-04-20Q1615721002ND
2016-04-20Q16157210033.36 ppb
2016-04-20Q16157210052.10 ppb
2016-04-20Q16157210144.67 ppb
2016-04-20Q16157210151.91 ppb
2016-04-20Q16157210164.49 ppb
2016-04-20Q16157210174.64 ppb
2016-06-16Q1624597001ND
2016-09-06Q16353940017.86 ppb
2016-09-06Q163539400210.4 ppb
2016-09-06Q16353940037.90 ppb
2016-09-06Q16353940049.94 ppb
2016-10-20Q1644787004ND
2016-10-20Q16447870104.80 ppb
2016-10-20Q1644787006ND
2016-10-20Q16447870127.55 ppb
2016-10-20Q1644787007ND
2016-11-08Q1648213030ND
2016-11-08Q1648213032ND
2016-11-08Q1648213035ND
2016-11-08Q1648213036ND
2016-11-08Q16482130185.76 ppb
2016-11-08Q16482130195.74 ppb
2016-11-08Q16482130205.52 ppb
2016-11-08Q16482130214.95 ppb
2017-01-31Q1704122013ND
2017-01-31Q17041220152.38 ppb
2017-01-31Q17041220094.24 ppb
2017-01-31Q17041220104.38 ppb
2017-01-31Q17041220114.23 ppb
2017-01-31Q17041220244.46 ppb
2017-04-18Q17158050024.41 ppb
2017-04-18Q17158050034.78 ppb
2017-04-18Q17158050044.20 ppb
2017-04-18Q17158050054.47 ppb
2017-07-18Q17295120025.01 ppb
2017-07-18Q17295120035.16 ppb
2017-07-18Q17295120045.32 ppb
2017-07-18Q17295120055.34 ppb
2017-10-17Q17532930352.53 ppb
2017-10-17Q1753293001ND
2017-10-17Q17532930373.61 ppb
2017-10-17Q17532930333.18 ppb
2017-10-17Q1753293039ND
2017-10-17Q17532930323.98 ppb
2017-10-17Q17532930284.90 ppb
2017-10-17Q17532930233.87 ppb
2017-10-17Q17532930064.52 ppb
2017-10-17Q1753293030ND
2017-11-01Q17562230202.52 ppb
2017-11-01Q17562230222.67 ppb
2017-11-01Q1756223002ND
2017-11-01Q1756223023ND
2017-11-01Q1756223014ND
2017-11-01Q1756223042ND
2017-11-01Q1756223025ND
2018-02-21Q1807322004ND
2018-02-21Q18073220063.00 ppb
2018-02-21Q1807322007ND
2018-02-21Q18073220022.94 ppb
2018-02-21Q18073220082.80 ppb
2018-05-16Q1819957002ND
2018-05-16Q1819957003ND
2018-05-16Q1819957005ND
2018-05-16Q18199570082.01 ppb
2018-05-16Q1819957010ND
2018-05-16Q1819957011ND
2018-05-16Q18199570142.45 ppb
2018-05-16Q1819957015ND
2018-05-16Q1819957017ND
2018-05-16Q18199570362.95 ppb
2018-05-16Q18199570372.82 ppb
2018-05-16Q18199570383.86 ppb
2018-05-16Q18199570392.74 ppb
2018-07-25Q18296070027.59 ppb
2018-07-25Q18296070037.18 ppb
2018-07-25Q18296070048.16 ppb
2018-07-25Q18296070059.95 ppb
2018-10-19Q1842052014ND
2018-10-19Q1842052015ND
2018-10-19Q1842052017ND
2018-10-19Q1842052020ND
2018-10-19Q1842052022ND
2018-10-19Q18420520096.18 ppb
2018-10-19Q18420520102.55 ppb
2018-10-19Q18420520115.78 ppb
2018-10-19Q18420520126.79 ppb
2019-01-15Q1901990002ND
2019-01-15Q1901990003ND
2019-01-15Q1901990005ND
2019-01-15Q19019900136.72 ppb
2019-01-15Q19019900146.97 ppb
2019-01-15Q19019900156.75 ppb
2019-01-15Q19019900166.93 ppb
2019-04-11Q1914886003ND
2019-04-11Q1914886004ND
2019-04-11Q1914886007ND
2019-04-11Q19148860081.23 ppb
2019-04-11Q1914886010ND
2019-04-11Q19148860123.15 ppb
2019-04-11Q19148860304.51 ppb
2019-04-11Q1914886031ND
2019-04-11Q19148860324.71 ppb
2019-04-11Q19148860334.57 ppb
2019-08-06Q19516200024.59 ppb
2019-08-06Q19516200035.54 ppb
2019-08-06Q19516200045.28 ppb
2019-08-06Q19516200055.07 ppb
2019-10-07Q19717840073.19 ppb
2019-10-07Q19717840034.35 ppb
2019-10-07Q19717840044.94 ppb
2019-10-07Q19717840054.97 ppb
2019-10-07Q19717840065.19 ppb