Total trihalomethanes (TTHMs)
Middletown 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.
Samples
Samples exceeding legal limit (MCL)
Samples exceeding
health guidelines
Testing results - average by year
| Year | Average result | Samples taken | Detections | Range of results |
|---|---|---|---|---|
| 2018 | 54.5 ppb | 16 | 16 | 27.8 ppb - 88.8 ppb |
| 2019 | 54.7 ppb | 16 | 16 | 33.6 ppb - 86.3 ppb |
| 2020 | 47.2 ppb | 16 | 16 | 24.0 ppb - 89.2 ppb |
| 2021 | 50.0 ppb | 16 | 16 | 21.2 ppb - 103.1 ppb |
| 2022 | 42.9 ppb | 16 | 16 | 26.1 ppb - 73.4 ppb |
| 2023 | 49.4 ppb | 16 | 16 | 25.3 ppb - 103.7 ppb |
ppb = parts per billion
State, National, and Health Guidelines for Drinking Water
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 |
|---|---|---|
| 2018-01-05 | DBP 200485411 | 32.5 ppb |
| 2018-01-05 | DBP 200485412 | 62.0 ppb |
| 2018-01-05 | DBP 200485413 | 35.8 ppb |
| 2018-01-05 | DBP 200485410 | 27.8 ppb |
| 2018-04-05 | DBP 200491446 | 37.1 ppb |
| 2018-04-05 | DBP 200491447 | 35.0 ppb |
| 2018-04-05 | DBP 200491448 | 38.5 ppb |
| 2018-04-05 | DBP 200491449 | 35.8 ppb |
| 2018-07-04 | DBP 200498638 | 69.4 ppb |
| 2018-07-04 | DBP 200498639 | 62.6 ppb |
| 2018-07-04 | DBP 200498640 | 74.3 ppb |
| 2018-07-04 | DBP 200498641 | 88.8 ppb |
| 2018-10-04 | DBP 200508048 | 62.3 ppb |
| 2018-10-04 | DBP 200508050 | 72.6 ppb |
| 2018-10-04 | DBP 200508049 | 74.3 ppb |
| 2018-10-04 | DBP 200508047 | 63.3 ppb |
| 2019-01-03 | DBP 200517506 | 33.6 ppb |
| 2019-01-03 | DBP 200517507 | 36.4 ppb |
| 2019-01-03 | DBP 200517508 | 67.6 ppb |
| 2019-01-03 | DBP 200517509 | 39.9 ppb |
| 2019-04-04 | DBP 200527182 | 45.5 ppb |
| 2019-04-04 | DBP 200527183 | 43.0 ppb |
| 2019-04-04 | DBP 200527184 | 52.3 ppb |
| 2019-04-04 | DBP 200527185 | 53.5 ppb |
| 2019-07-03 | DBP 200538923 | 63.1 ppb |
| 2019-07-03 | DBP 200538925 | 84.3 ppb |
| 2019-07-03 | DBP 200538924 | 82.3 ppb |
| 2019-07-03 | DBP 200538922 | 86.3 ppb |
| 2019-10-17 | DBP 200553335 | 49.2 ppb |
| 2019-10-17 | DBP 200553337 | 49.7 ppb |
| 2019-10-17 | DBP 200553339 | 51.5 ppb |
| 2019-10-17 | DBP 200553333 | 37.5 ppb |
| 2020-01-09 | DBP 200562313 | 24.0 ppb |
| 2020-01-09 | DBP 200562314 | 26.8 ppb |
| 2020-01-09 | DBP 200562315 | 33.0 ppb |
| 2020-01-09 | DBP 200562316 | 28.8 ppb |
| 2020-04-09 | DBP 200571896 | 41.9 ppb |
| 2020-04-09 | DBP 200571897 | 45.9 ppb |
| 2020-04-09 | DBP 200571895 | 47.1 ppb |
| 2020-04-09 | DBP 200571893 | 47.1 ppb |
| 2020-07-09 | DBP 200582084 | 68.6 ppb |
| 2020-07-09 | DBP 200582085 | 61.5 ppb |
| 2020-07-09 | DBP 200582086 | 66.5 ppb |
| 2020-07-09 | DBP 200582087 | 89.2 ppb |
| 2020-10-15 | DBP 200594167 | 40.4 ppb |
| 2020-10-15 | DBP 200594168 | 39.3 ppb |
| 2020-10-15 | DBP 200594169 | 44.4 ppb |
| 2020-10-15 | DBP 200594170 | 50.1 ppb |
| 2021-01-14 | DBP 200603902 | 30.1 ppb |
| 2021-01-14 | DBP 200603899 | 31.6 ppb |
| 2021-01-14 | DBP 200603900 | 28.0 ppb |
| 2021-01-14 | DBP 200603901 | 21.2 ppb |
| 2021-04-15 | DBP 200613338 | 29.1 ppb |
| 2021-04-15 | DBP 200613339 | 28.0 ppb |
| 2021-04-15 | DBP 200613340 | 39.6 ppb |
| 2021-04-15 | DBP 200613337 | 40.9 ppb |
| 2021-07-08 | DBP 200623691 | 63.0 ppb |
| 2021-07-08 | DBP 200623693 | 63.7 ppb |
| 2021-07-08 | DBP 200623708 | 63.0 ppb |
| 2021-07-08 | DBP 200623709 | 85.7 ppb |
| 2021-10-21 | B300086252 300086254 | 55.4 ppb |
| 2021-10-21 | B300086249 300086251 | 103.1 ppb |
| 2021-10-21 | B300086246 300086248 | 71.9 ppb |
| 2021-10-21 | B300086243 300086245 | 45.5 ppb |
| 2022-01-06 | D300128620 300128622 | 38.5 ppb |
| 2022-01-06 | D300128623 300128625 | 33.8 ppb |
| 2022-01-06 | D300128626 300128628 | 40.5 ppb |
| 2022-01-06 | D300128629 300128631 | 34.3 ppb |
| 2022-04-07 | D300167654 300167656 | 32.7 ppb |
| 2022-04-07 | D300167657 300167659 | 27.6 ppb |
| 2022-04-07 | D300167660 300167662 | 32.2 ppb |
| 2022-04-07 | D300167663 300167665 | 26.1 ppb |
| 2022-07-07 | D300209440 300209442 | 63.7 ppb |
| 2022-07-07 | D300209434 300209436 | 56.9 ppb |
| 2022-07-07 | D300209431 300209433 | 60.9 ppb |
| 2022-07-07 | D300209437 300209439 | 73.4 ppb |
| 2022-10-27 | D300264516 300264518 | 46.3 ppb |
| 2022-10-27 | D300264519 300264521 | 34.8 ppb |
| 2022-10-27 | D300264522 300264524 | 53.9 ppb |
| 2022-10-27 | D300264525 300264527 | 31.0 ppb |
| 2023-01-12 | D300297210 300297212 | 30.7 ppb |
| 2023-01-12 | D300297213 300297215 | 25.3 ppb |
| 2023-01-12 | D300297216 300297218 | 34.0 ppb |
| 2023-01-12 | D300297219 300297221 | 34.2 ppb |
| 2023-04-20 | D300336742 300336744 | 37.6 ppb |
| 2023-04-20 | D300336748 300336750 | 54.9 ppb |
| 2023-04-20 | D300336745 300336747 | 46.1 ppb |
| 2023-04-20 | D300336739 300336741 | 43.0 ppb |
| 2023-07-06 | D300377098 300377100 | 76.3 ppb |
| 2023-07-06 | D300377101 300377103 | 81.4 ppb |
| 2023-07-06 | D300377104 300377106 | 103.7 ppb |
| 2023-07-06 | D300377107 300377109 | 71.3 ppb |
| 2023-10-19 | D300433229 300433231 | 36.7 ppb |
| 2023-10-19 | D300433232 300433234 | 33.4 ppb |
| 2023-10-19 | D300433235 300433237 | 51.8 ppb |
| 2023-10-19 | D300433238 300433240 | 30.7 ppb |