Haloacetic acids (HAA5)
Bear Mountain Water Supply
Haloacetic acids are formed when disinfectants such as chlorine are added to tap water. The group of five haloacetic acids regulated by federal standards includes monochloroacetic acid, dichloroacetic acid, trichloroacetic acid, monobromoacetic acid and dibromoacetic acid. Read More.
Haloacetic acids are harmful during pregnancy and may increase the risk of cancer. Haloacetic acids are� genotoxic, which means that they induce mutations and DNA damage. Multiple studies by the National Toxicology Program have demonstrated the cancer-causing properties of individual haloacetic acids in laboratory animals. The Department of Health and Human Services is currently considering listing di- or tri-haloacetic acids for possible inclusion in its comprehensive Report on Carcinogens.
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 | 39.7 ppb | 4 | 4 | 16.9 ppb - 65.0 ppb |
| 2019 | 27.6 ppb | 5 | 5 | 10.4 ppb - 55.0 ppb |
| 2020 | 48.7 ppb | 4 | 4 | 14.6 ppb - 77.0 ppb |
| 2021 | 30.6 ppb | 4 | 4 | 9.83 ppb - 50.0 ppb |
| 2022 | 61.7 ppb | 2 | 2 | 53.4 ppb - 70.0 ppb |
| 2023 | 25.8 ppb | 5 | 5 | 14.1 ppb - 48.0 ppb |
ppb = parts per billion
State, National, and Health Guidelines for Drinking Water
EWG Health Guideline: 0.1 ppb
The EWG Health Guideline of 0.1 ppb for the group of five haloacetic acids, or HAA5, was defined in a peer-reviewed scientific study by EWG and represents a one-in-a-million lifetime cancer risk level. This health guideline protects against cancer.
EPA Maximum Contaminant
Level (MCL): 60 ppb
The legal limit for the group of five haloacetic acids (HAA5), 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 and harm to the developing fetus due to exposure to haloacetic acids.
ppb = parts per billion
All test results
| Date | Lab ID | Result |
|---|---|---|
| 2018-02-05 | THAAS 02061811:4 | 16.9 ppb |
| 2018-05-07 | HAA5 05071819-2 | 30.0 ppb |
| 2018-07-25 | HAA5 08091821-6 | 65.0 ppb |
| 2018-11-13 | HAA5 11151803: 2 | 47.0 ppb |
| 2019-02-05 | HAA5 02061903A:2 | 10.4 ppb |
| 2019-02-05 | HAA5S 02061903A:1 | 10.4 ppb |
| 2019-05-07 | HAA5S 05091905 | 21.0 ppb |
| 2019-08-07 | HAA5 08141907 | 55.0 ppb |
| 2019-11-04 | HAA5S QB192748 | 41.0 ppb |
| 2020-02-04 | DBP 02062004:2 | 14.6 ppb |
| 2020-05-13 | DBP9 05132006:2 | 31.0 ppb |
| 2020-08-13 | HAA5 08132013:2 | 72.0 ppb |
| 2020-11-04 | DBP 11042008-2 | 77.0 ppb |
| 2021-02-16 | HAA5 11042008:2 | 9.83 ppb |
| 2021-05-05 | DBP 05052105:2 | 17.5 ppb |
| 2021-08-03 | HAA5S 08042105C:2 | 50.0 ppb |
| 2021-11-17 | HAA5S 11172114:2 | 45.0 ppb |
| 2022-09-14 | HAA5S 09142230-4 | 70.0 ppb |
| 2022-10-25 | HAA5S 10262215B:5 | 53.4 ppb |
| 2023-01-19 | HAA5S 01192309-1 | 20.0 ppb |
| 2023-06-15 | HAA5 06152304:2 | 32.7 ppb |
| 2023-09-26 | HAA5 10042313B2 | 48.0 ppb |
| 2023-10-06 | HAA5 12132334:2 | 14.1 ppb |
| 2023-12-06 | HAA5 12132334-2 | 14.1 ppb |