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EWG's Tap Water Database — 2019 UPDATE

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Total trihalomethanes (TTHMs)

Moscow Water Department

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.

 

62

Samples

0

Samples exceeding legal limit (MCL)

54

Samples exceeding
health guidelines

Testing results - average by year

 
YearAverage resultSamples takenDetectionsRange of results
20121.80 ppb20200.250 ppb - 4.97 ppb
20131.63 ppb1918ND - 3.95 ppb
20142.61 ppb1210ND - 5.42 ppb
20152.65 ppb221.14 ppb - 4.16 ppb
20160.514 ppb72ND - 2.53 ppb
20171.90 ppb221.17 ppb - 2.62 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
2012-03-19D120319034-0014.50 ppb
2012-03-19D120319034-0023.74 ppb
2012-03-19D120319034-0030.490 ppb
2012-03-19D120319034-0040.400 ppb
2012-03-19D120319034-0052.62 ppb
2012-06-11D120611025-0050.390 ppb
2012-06-11D120611025-0040.270 ppb
2012-06-11D120611025-0030.310 ppb
2012-06-11D120611025-0020.310 ppb
2012-06-11D120611025-0010.260 ppb
2012-09-18D120918036-0052.42 ppb
2012-09-18D120918036-0041.69 ppb
2012-09-18D120918036-0031.04 ppb
2012-09-18D120918036-0020.560 ppb
2012-09-18D120918036-0014.97 ppb
2012-10-17D121018005-0051.68 ppb
2012-10-17D121018005-0042.96 ppb
2012-10-17D121018005-0032.32 ppb
2012-10-17D121018005-0020.250 ppb
2012-10-17D121018005-0014.77 ppb
2013-03-07D130308001-0012.76 ppb
2013-03-07D130308001-0023.18 ppb
2013-03-07D130308001-0033.78 ppb
2013-03-07D130308001-0040.290 ppb
2013-03-07D130308001-0050.290 ppb
2013-06-17D130617032-0051.79 ppb
2013-06-17D130617032-0040.280 ppb
2013-06-17D130617032-0030.370 ppb
2013-06-17D130617032-0020.280 ppb
2013-06-17D130617032-0010.290 ppb
2013-09-09D130909037-0052.56 ppb
2013-09-09D130909037-004ND
2013-09-09D130909037-0030.290 ppb
2013-09-09D130909037-0022.69 ppb
2013-09-09D130909037-0013.95 ppb
2013-12-12D131212007-0010.340 ppb
2013-12-12D131212007-0020.990 ppb
2013-12-12D131212007-0033.92 ppb
2013-12-12D131212007-0042.91 ppb
2014-03-10D140310018-0045.42 ppb
2014-03-10D140310018-0034.61 ppb
2014-03-10D140310018-0024.29 ppb
2014-03-10D140310018-0012.09 ppb
2014-06-16D140616029-0015.15 ppb
2014-06-16D140616029-0021.73 ppb
2014-06-16D140616029-0030.400 ppb
2014-06-16D140616029-0042.38 ppb
2014-09-10D140910030-004ND
2014-09-10D140910030-0034.78 ppb
2014-09-10D140910030-0020.430 ppb
2014-09-10D140910030-001ND
2015-08-26D150826041-0011.14 ppb
2015-08-31D150831013-0014.16 ppb
2016-03-31V160331025-005ND
2016-03-31V160331025-004ND
2016-03-31V160331025-003ND
2016-03-31V160331025-002ND
2016-03-31V160331025-001ND
2016-09-12D160912052-0012.53 ppb
2016-09-12D160912052-0021.07 ppb
2017-08-08D170808042-0011.17 ppb
2017-08-08D170808042-0022.62 ppb