Total trihalomethanes (TTHMs)
New Britain 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 | 42.3 ppb | 33 | 33 | 19.6 ppb - 76.4 ppb |
| 2019 | 39.7 ppb | 32 | 32 | 14.0 ppb - 80.4 ppb |
| 2020 | 33.4 ppb | 35 | 35 | 11.0 ppb - 87.1 ppb |
| 2021 | 36.5 ppb | 32 | 32 | 13.3 ppb - 70.8 ppb |
| 2022 | 41.4 ppb | 34 | 34 | 1.20 ppb - 85.6 ppb |
| 2023 | 38.7 ppb | 32 | 32 | 11.3 ppb - 84.5 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 |
|---|---|---|
| 2018-02-22 | DBP 200488580 | 23.1 ppb |
| 2018-02-22 | DBP 200488581 | 19.6 ppb |
| 2018-02-22 | DBP 200488582 | 29.0 ppb |
| 2018-02-22 | DBP 200488583 | 29.4 ppb |
| 2018-02-22 | DBP 200488584 | 25.1 ppb |
| 2018-02-22 | DBP 200488585 | 44.2 ppb |
| 2018-02-22 | DBP 200488586 | 45.3 ppb |
| 2018-02-22 | DBP 200488587 | 34.8 ppb |
| 2018-05-16 | DBP 200494888 | 27.7 ppb |
| 2018-05-16 | DBP 200494889 | 23.2 ppb |
| 2018-05-16 | DBP 200494890 | 30.9 ppb |
| 2018-05-16 | DBP 200494891 | 34.4 ppb |
| 2018-05-16 | DBP 200494892 | 29.1 ppb |
| 2018-05-16 | DBP 200494893 | 48.3 ppb |
| 2018-05-16 | DBP 200494894 | 46.4 ppb |
| 2018-05-16 | DBP 200494895 | 40.1 ppb |
| 2018-08-14 | DBP 200502300 | 49.0 ppb |
| 2018-08-14 | DBP 200502301 | 44.4 ppb |
| 2018-08-14 | DBP 200502302 | 57.3 ppb |
| 2018-08-14 | DBP 200502303 | 60.6 ppb |
| 2018-08-14 | DBP 200502304 | 52.4 ppb |
| 2018-08-14 | DBP 200502305 | 75.1 ppb |
| 2018-08-14 | DBP 200502306 | 71.5 ppb |
| 2018-08-14 | DBP 200502307 | 76.4 ppb |
| 2018-11-14 | DBP 200512645 | 33.1 ppb |
| 2018-11-14 | DBP 200512646 | 25.7 ppb |
| 2018-11-14 | DBP 200512647 | 37.5 ppb |
| 2018-11-14 | DBP 200512648 | 43.5 ppb |
| 2018-11-14 | DBP 200512649 | 35.3 ppb |
| 2018-11-14 | DBP 200512650 | 63.3 ppb |
| 2018-11-14 | DBP 200512651 | 59.5 ppb |
| 2018-11-14 | DBP 200512652 | 46.5 ppb |
| 2018-11-14 | DBP 200512654 | 33.2 ppb |
| 2019-02-20 | DBP 200522297 | 15.2 ppb |
| 2019-02-20 | DBP 200522298 | 14.0 ppb |
| 2019-02-20 | DBP 200522299 | 20.3 ppb |
| 2019-02-20 | DBP 200522300 | 25.3 ppb |
| 2019-02-20 | DBP 200522301 | 18.9 ppb |
| 2019-02-20 | DBP 200522302 | 36.4 ppb |
| 2019-02-20 | DBP 200522303 | 35.7 ppb |
| 2019-02-20 | DBP 200522304 | 23.6 ppb |
| 2019-05-16 | DBP 200532562 | 27.2 ppb |
| 2019-05-16 | DBP 200532563 | 22.5 ppb |
| 2019-05-16 | DBP 200532564 | 31.3 ppb |
| 2019-05-16 | DBP 200532565 | 35.1 ppb |
| 2019-05-16 | DBP 200532566 | 30.2 ppb |
| 2019-05-16 | DBP 200532567 | 54.4 ppb |
| 2019-05-16 | DBP 200532568 | 42.7 ppb |
| 2019-05-16 | DBP 200532569 | 38.2 ppb |
| 2019-08-20 | DBP 200545574 | 42.5 ppb |
| 2019-08-20 | DBP 200545575 | 42.0 ppb |
| 2019-08-20 | DBP 200545576 | 64.0 ppb |
| 2019-08-20 | DBP 200545577 | 73.7 ppb |
| 2019-08-20 | DBP 200545578 | 52.5 ppb |
| 2019-08-20 | DBP 200545579 | 79.3 ppb |
| 2019-08-20 | DBP 200545580 | 77.4 ppb |
| 2019-08-20 | DBP 200545581 | 80.4 ppb |
| 2019-11-21 | DBP 200557689 | 25.4 ppb |
| 2019-11-21 | DBP 200557690 | 22.0 ppb |
| 2019-11-21 | DBP 200557691 | 33.5 ppb |
| 2019-11-21 | DBP 200557692 | 34.5 ppb |
| 2019-11-21 | DBP 200557693 | 28.7 ppb |
| 2019-11-21 | DBP 200557694 | 56.2 ppb |
| 2019-11-21 | DBP 200557695 | 51.2 ppb |
| 2019-11-21 | DBP 200557696 | 34.9 ppb |
| 2020-02-20 | DBP 200566934 | 11.9 ppb |
| 2020-02-20 | DBP 200566935 | 11.0 ppb |
| 2020-02-20 | DBP 200566936 | 17.7 ppb |
| 2020-02-20 | DBP 200566937 | 19.3 ppb |
| 2020-02-20 | DBP 200566938 | 12.8 ppb |
| 2020-02-20 | DBP 200566939 | 35.8 ppb |
| 2020-02-20 | DBP 200566940 | 24.7 ppb |
| 2020-02-20 | DBP 200566941 | 20.0 ppb |
| 2020-02-20 | DBP 200566944 | 12.5 ppb |
| 2020-05-13 | DBP 200575541 | 24.5 ppb |
| 2020-05-13 | DBP 200575542 | 20.7 ppb |
| 2020-05-13 | DBP 200575543 | 28.5 ppb |
| 2020-05-13 | DBP 200575544 | 32.7 ppb |
| 2020-05-13 | DBP 200575545 | 26.6 ppb |
| 2020-05-13 | DBP 200575546 | 44.1 ppb |
| 2020-05-13 | DBP 200575547 | 41.0 ppb |
| 2020-05-13 | DBP 200575548 | 41.5 ppb |
| 2020-08-11 | DBP 200585918 | 43.9 ppb |
| 2020-08-11 | DBP 200585919 | 38.0 ppb |
| 2020-08-11 | DBP 200585920 | 50.1 ppb |
| 2020-08-11 | DBP 200585921 | 58.8 ppb |
| 2020-08-11 | DBP 200585922 | 45.9 ppb |
| 2020-08-11 | DBP 200585923 | 74.6 ppb |
| 2020-08-11 | DBP 200585924 | 76.7 ppb |
| 2020-08-11 | DBP 200585925 | 87.1 ppb |
| 2020-08-11 | DBP 200585968 | 43.4 ppb |
| 2020-11-18 | DBP 200598654 | 18.1 ppb |
| 2020-11-18 | DBP 200598655 | 16.3 ppb |
| 2020-11-18 | DBP 200598656 | 22.9 ppb |
| 2020-11-18 | DBP 200598657 | 23.7 ppb |
| 2020-11-18 | DBP 200598658 | 35.4 ppb |
| 2020-11-18 | DBP 200598659 | 35.3 ppb |
| 2020-11-18 | DBP 200598660 | 34.6 ppb |
| 2020-11-18 | DBP 200598661 | 24.1 ppb |
| 2020-11-18 | DBP 200598662 | 16.3 ppb |
| 2021-02-17 | DBP 200607067 | 14.2 ppb |
| 2021-02-17 | DBP 200607068 | 13.3 ppb |
| 2021-02-17 | DBP 200607069 | 17.8 ppb |
| 2021-02-17 | DBP 200607070 | 19.9 ppb |
| 2021-02-17 | DBP 200607071 | 34.1 ppb |
| 2021-02-17 | DBP 200607072 | 31.8 ppb |
| 2021-02-17 | DBP 200607073 | 27.2 ppb |
| 2021-02-17 | DBP 200607074 | 23.8 ppb |
| 2021-05-20 | DBP 200618015 | 20.9 ppb |
| 2021-05-20 | DBP 200618016 | 17.8 ppb |
| 2021-05-20 | DBP 200618017 | 31.5 ppb |
| 2021-05-20 | DBP 200618018 | 27.9 ppb |
| 2021-05-20 | DBP 200618019 | 24.8 ppb |
| 2021-05-20 | DBP 200618020 | 38.3 ppb |
| 2021-05-20 | DBP 200618021 | 33.6 ppb |
| 2021-05-20 | DBP 200618022 | 29.3 ppb |
| 2021-08-11 | DBP 200628130 | 44.8 ppb |
| 2021-08-11 | DBP 200628131 | 39.7 ppb |
| 2021-08-11 | DBP 200628132 | 57.9 ppb |
| 2021-08-11 | DBP 200628133 | 58.0 ppb |
| 2021-08-11 | DBP 200628134 | 48.0 ppb |
| 2021-08-11 | DBP 200628135 | 70.0 ppb |
| 2021-08-11 | DBP 200628136 | 70.8 ppb |
| 2021-08-11 | DBP 200628137 | 62.5 ppb |
| 2021-11-17 | D300103908 300103910 | 28.7 ppb |
| 2021-11-17 | D300103911 300103913 | 26.9 ppb |
| 2021-11-17 | D300103914 300103916 | 37.5 ppb |
| 2021-11-17 | D300103917 300103919 | 40.0 ppb |
| 2021-11-17 | D300103920 300103922 | 32.4 ppb |
| 2021-11-17 | D300103923 300103925 | 48.1 ppb |
| 2021-11-17 | D300103926 300103928 | 53.1 ppb |
| 2021-11-17 | D300103929 300103931 | 42.5 ppb |
| 2022-02-15 | D300145868 300145870 | 16.8 ppb |
| 2022-02-15 | D300145871 300145873 | 14.6 ppb |
| 2022-02-15 | D300145874 300145876 | 22.8 ppb |
| 2022-02-15 | D300145877 300145879 | 24.6 ppb |
| 2022-02-15 | D300145880 300145882 | 17.9 ppb |
| 2022-02-15 | D300145883 300145885 | 33.9 ppb |
| 2022-02-15 | D300145886 300145888 | 34.7 ppb |
| 2022-02-15 | D300145889 300145891 | 25.5 ppb |
| 2022-02-15 | D300145892 300145894 | 1.20 ppb |
| 2022-05-10 | D300181521 300181523 | 28.5 ppb |
| 2022-05-10 | D300181524 300181526 | 27.2 ppb |
| 2022-05-10 | D300181527 300181529 | 39.3 ppb |
| 2022-05-10 | D300181530 300181532 | 41.0 ppb |
| 2022-05-10 | D300181533 300181535 | 31.2 ppb |
| 2022-05-10 | D300181536 300181538 | 46.8 ppb |
| 2022-05-10 | D300181539 300181541 | 52.6 ppb |
| 2022-05-10 | D300181542 300181544 | 42.4 ppb |
| 2022-05-10 | D300181545 300181547 | 29.1 ppb |
| 2022-08-09 | D300227257 300227259 | 53.2 ppb |
| 2022-08-09 | D300227260 300227262 | 46.2 ppb |
| 2022-08-09 | D300227263 300227265 | 71.5 ppb |
| 2022-08-09 | D300227266 300227268 | 75.2 ppb |
| 2022-08-09 | D300227269 300227271 | 61.7 ppb |
| 2022-08-09 | D300227272 300227274 | 85.6 ppb |
| 2022-08-09 | D300227275 300227277 | 79.7 ppb |
| 2022-08-09 | D300227278 300227280 | 80.7 ppb |
| 2022-11-15 | D300273443 300273446 | 29.4 ppb |
| 2022-11-15 | D300273450 300273454 | 27.3 ppb |
| 2022-11-15 | D300273456 300273461 | 37.3 ppb |
| 2022-11-15 | D300273462 300273464 | 40.0 ppb |
| 2022-11-15 | D300273465 300273467 | 32.6 ppb |
| 2022-11-15 | D300273468 300273470 | 55.7 ppb |
| 2022-11-15 | D300273471 300273473 | 56.1 ppb |
| 2022-11-15 | D300273474 300273476 | 46.2 ppb |
| 2023-02-09 | D300307705 300307707 | 12.3 ppb |
| 2023-02-09 | D300307708 300307710 | 11.3 ppb |
| 2023-02-09 | D300307711 300307713 | 21.0 ppb |
| 2023-02-09 | D300307714 300307716 | 18.8 ppb |
| 2023-02-09 | D300307717 300307719 | 33.5 ppb |
| 2023-02-09 | D300307720 300307722 | 25.3 ppb |
| 2023-02-09 | D300307723 300307725 | 14.2 ppb |
| 2023-02-09 | D300307726 300307728 | 25.2 ppb |
| 2023-05-11 | D300349330 300349332 | 25.3 ppb |
| 2023-05-11 | D300349333 300349335 | 22.5 ppb |
| 2023-05-11 | D300349336 300349338 | 50.8 ppb |
| 2023-05-11 | D300349339 300349341 | 34.6 ppb |
| 2023-05-11 | D300349342 300349344 | 28.6 ppb |
| 2023-05-11 | D300349345 300349347 | 41.0 ppb |
| 2023-05-11 | D300349348 300349350 | 46.2 ppb |
| 2023-05-11 | D300349351 300349353 | 36.2 ppb |
| 2023-08-16 | D300399298 300399300 | 57.4 ppb |
| 2023-08-16 | D300399301 300399303 | 51.7 ppb |
| 2023-08-16 | D300399304 300399306 | 80.8 ppb |
| 2023-08-16 | D300399307 300399309 | 69.9 ppb |
| 2023-08-16 | D300399310 300399312 | 59.0 ppb |
| 2023-08-16 | D300399313 300399315 | 84.5 ppb |
| 2023-08-16 | D300399316 300399318 | 80.1 ppb |
| 2023-08-16 | D300399319 300399321 | 76.7 ppb |
| 2023-11-16 | D300447192 300447194 | 21.2 ppb |
| 2023-11-16 | D300447195 300447197 | 19.3 ppb |
| 2023-11-16 | D300447198 300447200 | 27.9 ppb |
| 2023-11-16 | D300447201 300447203 | 28.8 ppb |
| 2023-11-16 | D300447204 300447206 | 23.7 ppb |
| 2023-11-16 | D300447207 300447209 | 38.5 ppb |
| 2023-11-16 | D300447210 300447212 | 39.3 ppb |
| 2023-11-16 | D300447213 300447215 | 31.7 ppb |