Dibromochloromethane
Holliston Water Department
Dibromochloromethane, one of the total trihalomethanes (TTHMs), is formed when chlorine or other disinfectants are used to treat drinking water. Dibromochloromethane and other disinfection byproducts increase the risk of cancer and may cause problems during pregnancy. Click here to read more about disinfection byproducts.
Samples
Samples exceeding legal limit (MCL)
Samples exceeding
health guidelines
Testing results - average by year
| Year | Average result | Samples taken | Detections | Range of results |
|---|---|---|---|---|
| 2014 | 0.688 ppb | 9 | 6 | ND - 1.30 ppb |
| 2015 | 5.27 ppb | 19 | 16 | ND - 11.0 ppb |
| 2016 | 5.61 ppb | 22 | 19 | ND - 12.0 ppb |
| 2017 | 0.687 ppb | 6 | 4 | ND - 2.09 ppb |
| 2018 | 3.99 ppb | 22 | 19 | ND - 8.10 ppb |
| 2019 | 3.92 ppb | 22 | 18 | ND - 9.76 ppb |
ppb = parts per billion
State and national drinking water standards and health guidelines
EWG Health Guideline 0.1 ppb
The EWG Health Guideline of 0.1 ppb for dibromochloromethane was proposed in 2018 by the California Office of Environmental Health Hazard Assessment as a one-in-a-million lifetime risk of cancer. Values greater than one-in-a-million cancer risk level can result in increased cancer cases above one in a million people.
ppb = parts per billion
All test results
| Date | Result |
|---|---|
| 2014-03-12 | 1.000 ppb |
| 2014-06-12 | ND |
| 2014-06-12 | 0.700 ppb |
| 2014-06-16 | 1.20 ppb |
| 2014-06-16 | ND |
| 2014-06-16 | ND |
| 2014-06-16 | 0.890 ppb |
| 2014-09-09 | 1.30 ppb |
| 2014-11-04 | 1.10 ppb |
| 2015-03-10 | 8.10 ppb |
| 2015-03-10 | 11.0 ppb |
| 2015-03-10 | 6.80 ppb |
| 2015-03-10 | 5.00 ppb |
| 2015-05-05 | 0.960 ppb |
| 2015-05-05 | ND |
| 2015-05-12 | 0.810 ppb |
| 2015-05-19 | ND |
| 2015-05-19 | ND |
| 2015-05-19 | 0.820 ppb |
| 2015-06-09 | 7.80 ppb |
| 2015-06-09 | 5.30 ppb |
| 2015-06-09 | 11.0 ppb |
| 2015-06-10 | 5.40 ppb |
| 2015-09-08 | 9.60 ppb |
| 2015-09-08 | 6.10 ppb |
| 2015-09-08 | 8.70 ppb |
| 2015-09-08 | 5.90 ppb |
| 2015-12-10 | 6.80 ppb |
| 2016-03-08 | 3.80 ppb |
| 2016-03-08 | 11.0 ppb |
| 2016-03-08 | 5.00 ppb |
| 2016-03-08 | 5.80 ppb |
| 2016-05-03 | 1.80 ppb |
| 2016-05-03 | ND |
| 2016-05-03 | ND |
| 2016-05-03 | 0.610 ppb |
| 2016-05-24 | ND |
| 2016-05-24 | 0.780 ppb |
| 2016-06-14 | 6.80 ppb |
| 2016-06-14 | 7.50 ppb |
| 2016-06-14 | 11.0 ppb |
| 2016-06-14 | 9.70 ppb |
| 2016-09-13 | 7.10 ppb |
| 2016-09-13 | 3.80 ppb |
| 2016-09-13 | 12.0 ppb |
| 2016-09-13 | 9.70 ppb |
| 2016-12-13 | 12.0 ppb |
| 2016-12-13 | 5.70 ppb |
| 2016-12-13 | 3.70 ppb |
| 2016-12-13 | 5.70 ppb |
| 2017-05-16 | 0.610 ppb |
| 2017-05-16 | 0.730 ppb |
| 2017-05-16 | 2.09 ppb |
| 2017-05-16 | 0.690 ppb |
| 2017-05-16 | ND |
| 2017-05-16 | ND |
| 2018-03-15 | 8.10 ppb |
| 2018-03-15 | 7.30 ppb |
| 2018-03-15 | 3.90 ppb |
| 2018-03-15 | 5.60 ppb |
| 2018-05-15 | 0.840 ppb |
| 2018-05-15 | ND |
| 2018-05-15 | 0.850 ppb |
| 2018-05-15 | ND |
| 2018-05-15 | 2.14 ppb |
| 2018-05-15 | ND |
| 2018-06-12 | 2.10 ppb |
| 2018-06-12 | 8.00 ppb |
| 2018-06-12 | 6.30 ppb |
| 2018-06-12 | 5.60 ppb |
| 2018-09-11 | 5.30 ppb |
| 2018-09-11 | 5.10 ppb |
| 2018-09-11 | 5.20 ppb |
| 2018-09-11 | 6.50 ppb |
| 2018-12-11 | 4.20 ppb |
| 2018-12-11 | 3.50 ppb |
| 2018-12-11 | 3.80 ppb |
| 2018-12-11 | 3.50 ppb |
| 2019-03-12 | 4.82 ppb |
| 2019-03-12 | 3.53 ppb |
| 2019-03-12 | 4.02 ppb |
| 2019-03-12 | 4.66 ppb |
| 2019-05-14 | ND |
| 2019-05-14 | 1.01 ppb |
| 2019-05-14 | ND |
| 2019-05-14 | ND |
| 2019-05-14 | ND |
| 2019-05-14 | 0.930 ppb |
| 2019-06-11 | 4.70 ppb |
| 2019-06-11 | 3.31 ppb |
| 2019-06-11 | 3.90 ppb |
| 2019-06-11 | 4.01 ppb |
| 2019-09-10 | 9.76 ppb |
| 2019-09-10 | 7.06 ppb |
| 2019-09-10 | 8.18 ppb |
| 2019-09-10 | 5.42 ppb |
| 2019-12-09 | 5.83 ppb |
| 2019-12-09 | 5.52 ppb |
| 2019-12-09 | 5.28 ppb |
| 2019-12-09 | 4.27 ppb |