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EWG's Tap Water Database — 2021 UPDATE

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Total trihalomethanes (TTHMs)

Falls Water Company Inc

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.

 

21

Samples

0

Samples exceeding legal limit (MCL)

5

Samples exceeding
health guidelines

Testing results - average by year

 
YearAverage resultSamples takenDetectionsRange of results
20141.97 ppb41ND - 7.88 ppb
20154.86 ppb224.40 ppb - 5.31 ppb
2016ND20ND
20170.155 ppb41ND - 0.620 ppb
20180.130 ppb41ND - 0.520 ppb
2019ND50ND

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
2014-09-29DI40928009ND
2014-09-29DI40928008ND
2014-09-29DI40928007ND
2014-09-29DI409280067.88 ppb
2015-09-22DI509197074.40 ppb
2015-09-22DI509197065.31 ppb
2016-09-28DI60931902ND
2016-09-28DI60931901ND
2017-07-06VI70704101ND
2017-07-06DI70704101ND
2017-08-10DI70812604ND
2017-08-10DI708126010.620 ppb
2018-08-08VI80810801ND
2018-09-26DI80927202ND
2018-09-26DI809272010.520 ppb
2018-11-14VI81110401ND
2019-03-25VI90316701ND
2019-03-25VI903167001ND
2019-04-01VI90400501ND
2019-09-24DI90930501ND
2019-09-24DI90930502ND