EWG's Tap Water Database — 2021 UPDATE


Total trihalomethanes (TTHMs)

Dewitt WDS - North

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.





Samples exceeding legal limit (MCL)


Samples exceeding
health guidelines

Testing results - average by year

YearAverage resultSamples takenDetectionsRange of results
201438.9 ppb161626.0 ppb - 52.0 ppb
201535.5 ppb161619.0 ppb - 58.0 ppb
201640.8 ppb161621.0 ppb - 61.0 ppb
201754.6 ppb121238.0 ppb - 85.0 ppb
201838.7 ppb161628.0 ppb - 53.0 ppb
201947.3 ppb161635.0 ppb - 68.0 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
2014-02-131Q2014 RUSSELL L27.0 ppb
2014-02-131Q2014 FLY RD43.0 ppb
2014-02-131Q2014 ALMONT DR31.0 ppb
2014-02-131Q2014 BADGELY R26.0 ppb
2014-05-132Q2014 FLY RD33.0 ppb
2014-05-132Q2014 RUSSELL L46.0 ppb
2014-05-132Q2014 ALMONT DR43.0 ppb
2014-05-132Q2014 BADGELY R36.0 ppb
2014-08-133Q2014 ALMONT DR51.0 ppb
2014-08-133Q2014 BADGELY R52.0 ppb
2014-08-133Q2014 FLY RD39.0 ppb
2014-08-133Q2014 RUSSELL L38.0 ppb
2014-11-134Q2014 RUSSELL L34.0 ppb
2014-11-134Q2014 FLY RD34.0 ppb
2014-11-134Q2014 BADGELY R41.0 ppb
2014-11-134Q2014 ALMONT DR49.0 ppb
2015-02-111Q2015 FLY RD19.0 ppb
2015-02-111Q2015 ALMONT DR21.6 ppb
2015-02-111Q2015 RUSSELL L21.7 ppb
2015-02-111Q2015 BADGELY R36.0 ppb
2015-05-142Q2015 RUSSELL L25.0 ppb
2015-05-142Q2015 FLY RD22.0 ppb
2015-05-142Q2015 ALMONT DR27.0 ppb
2015-05-142Q2015 BADGELY R29.0 ppb
2015-08-133Q2015 BADGELY R57.0 ppb
2015-08-133Q2015 ALMONT DR43.0 ppb
2015-08-133Q2015 RUSSELL L44.0 ppb
2015-08-133Q2015 FLY RD36.0 ppb
2015-11-094Q2015 RUSSELL L40.0 ppb
2015-11-094Q2015 BADGELY R58.0 ppb
2015-11-094Q2015 ALMONT DR42.0 ppb
2015-11-094Q2015 FLY RD46.0 ppb
2016-02-121Q2016 ALMONT DR24.0 ppb
2016-02-121Q2016 RUSSELL L22.0 ppb
2016-02-121Q2016 FLY RD21.0 ppb
2016-02-121Q2016 BADGELY R33.0 ppb
2016-05-172Q2016 FLY RD29.0 ppb
2016-05-172Q2016 BADGELY R41.0 ppb
2016-05-172Q2016 RUSSELL L35.0 ppb
2016-05-172Q2016 ALMONT DR33.0 ppb
2016-08-103Q2016 BADGELY R56.0 ppb
2016-08-103Q2016 RUSSELL L43.0 ppb
2016-08-103Q2016 FLY RD52.0 ppb
2016-08-103Q2016 ALMONT DR48.0 ppb
2016-11-084Q2016 BADGELY R61.0 ppb
2016-11-084Q2016 FLY RD51.0 ppb
2016-11-084Q2016 ALMONT DR45.0 ppb
2016-11-084Q2016 RUSSELL L59.0 ppb
2017-05-102Q2017 ALMONT DR50.0 ppb
2017-05-102Q2017 FLY RD54.0 ppb
2017-05-102Q2017 BADGELY R59.0 ppb
2017-05-102Q2017 RUSSELL L47.0 ppb
2017-08-093Q2017 RUSSELL L63.0 ppb
2017-08-093Q2017 BADGELY R85.0 ppb
2017-08-093Q2017 FLY RD71.0 ppb
2017-08-093Q2017 ALMONT DR64.0 ppb
2017-11-074Q2017 ALMONT DR40.0 ppb
2017-11-074Q2017 BADGELY R46.0 ppb
2017-11-074Q2017 RUSSELL L38.0 ppb
2017-11-074Q2017 FLY RD38.0 ppb
2018-02-151Q2018 ALMONT DR29.0 ppb
2018-02-151Q2018 FLY RD34.0 ppb
2018-02-151Q2018 RUSSELL L28.0 ppb
2018-02-151Q2018 BADGLEY R34.0 ppb
2018-05-102Q2018 FLY RD43.0 ppb
2018-05-102Q2018 RUSSELL L42.0 ppb
2018-05-102Q2018 ALMONT DR35.0 ppb
2018-05-102Q2018 BADGLEY R51.0 ppb
2018-08-143Q2018 RUSSELL L41.0 ppb
2018-08-143Q2018 FLY RD43.0 ppb
2018-08-143Q2018 ALMONT DR53.0 ppb
2018-08-143Q2018 BADGLEY R52.0 ppb
2018-11-074Q2018 FLY RD42.0 ppb
2018-11-074Q2018 ALMONT DR30.0 ppb
2018-11-074Q2018 RUSSELL L30.0 ppb
2018-11-074Q2018 BADGLEY R32.0 ppb
2019-02-141Q2019 ALMONT DR41.0 ppb
2019-02-141Q2019 FLY RD43.0 ppb
2019-02-141Q2019 RUSSELL L39.0 ppb
2019-02-141Q2019 BADGLEY R39.0 ppb
2019-05-102Q2019 RUSSELL L44.0 ppb
2019-05-102Q2019 BADGLEY R50.0 ppb
2019-05-102Q2019 FLY RD53.0 ppb
2019-05-102Q2019 ALMONT DR44.0 ppb
2019-08-133Q2019 FLY RD59.0 ppb
2019-08-133Q2019 ALMONT DR53.0 ppb
2019-08-133Q2019 RUSSELL L52.0 ppb
2019-08-133Q2019 BADGLEY R68.0 ppb
2019-11-064Q2019 BADGLEY R52.0 ppb
2019-11-064Q2019 ALMONT DR35.0 ppb
2019-11-064Q2019 FLY RD48.0 ppb
2019-11-064Q2019 RUSSELL L36.0 ppb