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EWG's Tap Water Database — 2021 UPDATE

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Total trihalomethanes (TTHMs)

Beauregard Water Authority

Trihalomethanes are cancer-causing contaminants that form during water treatment with chlorine and other disinfectants. The total trihalomethanes group includes four chemicals: chloroform, bromodichloromethane, dibromochloromethane and bromoform. Read More.

Studies conducted in the U.S. and Europe have found that drinking tap water that carries disinfection byproducts increases the risk of developing bladder cancer. In animal studies, all trihalomethanes cause liver, kidney and intestinal tumors. Some human epidemiological studies also reported an association between disinfection byproducts and an increased risk of problems during pregnancy, including spontaneous miscarriage, cardiovascular defects, neural tube defects and low birth weight.

The health guideline of 0.15 parts per billion, or ppb, for the group of four trihalomethanes, or THM4/TTHM, was defined in a peer-reviewed scientific study by EWG and represents a one-in-one-million lifetime cancer risk level.

Click here to read more about disinfection byproducts.

MORE ABOUT THIS CONTAMINANT

 

86

Samples

0

Samples exceeding legal limit (MCL)

7

Samples exceeding
health guidelines

Testing results - average by year

 
YearAverage resultSamples takenDetectionsRange of results
20140.178 ppb181ND - 3.20 ppb
2015ND140ND
2016ND140ND
20170.0857 ppb141ND - 1.20 ppb
2018ND120ND
20190.286 ppb146ND - 1.30 ppb

ppb = parts per billion

State and national drinking water standards and health guidelines

EWG Health Guideline 0.15 ppb

The health guideline of 0.15 parts per billion, or ppb, for the group of four trihalomethanes, or THM4/TTHM, was defined in a peer-reviewed scientific study by EWG and represents a one-in-one-million lifetime cancer risk level.

EPA Maximum Contaminant
Level (MCL) 80 ppb

The legal limit for the group of four trihalomethanes, established in 1998, was based on the need for residual disinfectant levels in water served to customers and the cost of treatment. This limit does not fully protect against the risk of cancer due to exposure to trihalomethanes.

ppb = parts per billion

All test results

Date Lab ID Result
2014-01-13AA88228ND
2014-01-14AA88230ND
2014-01-14AA88229ND
2014-01-14AA88232ND
2014-01-14AA88231ND
2014-04-16AA89109ND
2014-04-16AA89110ND
2014-04-16AA89111ND
2014-04-16AA89107ND
2014-04-16AA89108ND
2014-07-18AA90640ND
2014-07-18AA90642ND
2014-07-18AA90639ND
2014-07-18AA90641ND
2014-07-18AA90638ND
2014-10-14AA92136ND
2014-10-15AA92138ND
2014-10-15AA921373.20 ppb
2015-01-14AB02032ND
2015-01-14AB02031ND
2015-01-14AB02030ND
2015-04-14AB03301ND
2015-04-14AB03303ND
2015-04-14AB03302ND
2015-07-15AB06040ND
2015-07-15AB06036ND
2015-07-15AB06035ND
2015-10-13AB08337ND
2015-10-13AB08338ND
2015-10-13AB08336ND
2015-10-13AB08339ND
2015-10-13AB08340ND
2016-01-12AB09704ND
2016-01-12AB09708ND
2016-01-12AB09705ND
2016-01-12AB09707ND
2016-01-12AB09706ND
2016-04-13AB11113ND
2016-04-13AB11112ND
2016-04-13AB11111ND
2016-07-13AB13455ND
2016-07-13AB13454ND
2016-07-13AB13453ND
2016-10-12AB15785ND
2016-10-12AB15786ND
2016-10-13AB15784ND
2017-01-10AB17178ND
2017-01-10AB171771.20 ppb
2017-01-10AB17176ND
2017-04-11AB18596ND
2017-04-11AB18597ND
2017-04-11AB18598ND
2017-07-10AB2783ND
2017-07-10AB20782ND
2017-07-10AB20781ND
2017-07-10AB20780ND
2017-07-10AB20779ND
2017-10-13AB23704ND
2017-10-13AB23703ND
2017-10-13AB23705ND
2018-01-08AB24943ND
2018-01-08AB24942ND
2018-01-08AB24944ND
2018-04-11AB26330ND
2018-04-11AB26329ND
2018-04-11AB26328ND
2018-07-10AB28300ND
2018-07-10AB28299ND
2018-07-10AB28298ND
2018-10-09AB30828ND
2018-10-09AB30829ND
2018-10-09AB30827ND
2019-01-17AB326161.30 ppb
2019-01-17AB326170.600 ppb
2019-01-17AB326140.500 ppb
2019-01-17AB326150.200 ppb
2019-01-17AB326180.1000 ppb
2019-04-10AB34083ND
2019-04-10AB34082ND
2019-04-10AB34084ND
2019-04-10AB34081ND
2019-10-17AB394141.30 ppb
2019-10-17AB39413ND
2019-10-17AB39412ND
2019-10-17AB39411ND
2019-10-17AB39410ND