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EWG's Tap Water Database — 2019 UPDATE

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Total trihalomethanes (TTHMs)

Tract 349 Mutual Water Co.

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.

 

32

Samples

0

Samples exceeding legal limit (MCL)

5

Samples exceeding
health guidelines

Testing results - average by year

 
YearAverage resultSamples takenDetectionsRange of results
2012ND70ND
2013ND60ND
2014ND70ND
20151.40 ppb81ND - 11.2 ppb
201610.7 ppb227.00 ppb - 14.4 ppb
20178.70 ppb226.40 ppb - 11.0 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
2012-01-122706-002-0820ND
2012-01-232706-002-1230ND
2012-02-092706-002-1010ND
2012-04-242706-002-0900ND
2012-07-122706-002-0835ND
2012-10-222706-002-1040ND
2012-10-222706-003-1055ND
2013-01-212706-002-1140ND
2013-04-162706-002-0820ND
2013-09-272706-002-0825ND
2013-10-102706-002-0914ND
2013-10-242706-002-0900ND
2013-10-242706-003-0930ND
2014-02-069588-002-0916ND
2014-04-169588-002-1015ND
2014-07-319588-002-0915ND
2014-08-133761-801-0815ND
2014-08-133761-800-0835ND
2014-12-099588-003-0914ND
2014-12-129588-002-0938ND
2015-03-209588-002-0930ND
2015-04-249588-002-0940ND
2015-07-309588-002-1133ND
2015-08-053761-801-081811.2 ppb
2015-08-053761-800-0818ND
2015-09-259588-002-0905ND
2015-10-239588-002-0932ND
2015-10-269588-003-0929ND
2016-09-073761-801-10017.00 ppb
2016-09-073761-800-095914.4 ppb
2017-08-023761-801-10246.40 ppb
2017-08-023761-800-105911.0 ppb