Chloromethane
King County Water District #20
NOTE: King County Water District #20 purchases water from Seattle Public Utilities which is required to test for chloromethane. Sample information shown below was taken by Seattle Public Utilities.
Chloromethane is an industrial solvent, aerosol propellant and a refrigerant. It also forms as a byproduct of water disinfection. The EPA classifies chloromethane as possibly carcinogenic to humans.
Samples
Samples exceeding legal limit (MCL)
Samples exceeding
health guidelines
Testing results - average by year
| Year | Average result | Samples taken | Detections | Range of results |
|---|---|---|---|---|
| 2013 | ND | 1 | 0 | ND |
| 2014 | ND | 3 | 0 | ND |
| 2015 | ND | 9 | 0 | ND |
| 2016 | N/A | 0 | 0 | N/A |
| 2017 | ND | 2 | 0 | ND |
| 2018 | N/A | 0 | 0 | N/A |
| 2019 | N/A | 0 | 0 | N/A |
ppb = parts per billion
State and national drinking water standards and health guidelines
EWG Health Guideline 2.69 ppb
The EWG Health Guideline of 2.69 ppb for chloromethane was defined by the Environmental Protection Agency as a benchmark for testing under the Unregulated Contaminant Monitoring Rule program. This health guideline protects against cancer.
ppb = parts per billion
All test results
NOTE: King County Water District #20 purchases water from Seattle Public Utilities which is required to test for chloromethane. Sample information shown below was taken by Seattle Public Utilities.
| Date | Lab ID | Result |
|---|---|---|
| 2015-01-13 | 201501140525AM | ND |
| 2015-01-13 | 201501140778AM | ND |
| 2015-04-06 | 201504070229AM | ND |
| 2015-04-06 | 201504070359AM | ND |
| 2015-07-22 | 201507230482AM | ND |
| 2015-07-22 | 201507230496AM | ND |
| 2015-09-15 | 95609 | ND |
| 2015-10-13 | 201509280091AM | ND |
| 2015-10-13 | 201509280090AM | ND |
| 2017-03-07 | ND | |
| 2017-06-06 | ND |