Benzene
San Francisco City Water System
Benzene is a known human carcinogen. It also damages blood cells and the nervous system. Emissions from petroleum processing, hazardous waste landfills and underground storage tanks contaminate drinking water with benzene. Read More.
To protect against cancer risks, California set a public health goal for benzene in drinking water at 0.15 parts per billion, 30 times lower than the federal legal limit of 5 parts per billion.
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 | N/A | 0 | 0 | N/A |
| 2014 | N/A | 0 | 0 | N/A |
| 2015 | N/A | 0 | 0 | N/A |
| 2016 | ND | 1 | 0 | ND |
| 2017 | N/A | 0 | 0 | N/A |
| 2018 | ND | 17 | 0 | ND |
| 2019 | ND | 4 | 0 | ND |
ppb = parts per billion
State and national drinking water standards and health guidelines
EWG Health Guideline 0.15 ppb
The EWG Health Guideline of 0.15 ppb for benzene was defined by the California Office of Environmental Health Hazard Assessment as a public health goal, the level of a drinking water contaminant that does not pose a significant health risk. This health guideline protects against cancer.
EPA Maximum Contaminant
Level (MCL) 5 ppb
The legal limit for benzene, established in 1987, was based on analytical detection limits at the time that the standard was set. This limit may not fully protect against the risk of cancer due to benzene exposure.
ppb = parts per billion
All test results
| Date | Lab ID | Result |
|---|---|---|
| 2016-06-14 | 9553-001-0920 | ND |
| 2018-01-11 | 9553-007-1115 | ND |
| 2018-03-06 | 9590-004-1031 | ND |
| 2018-03-08 | 9590-006-0925 | ND |
| 2018-04-17 | 9590-007-1055 | ND |
| 2018-04-30 | 9590-008-1013 | ND |
| 2018-06-12 | 9590-008-0930 | ND |
| 2018-06-12 | 9590-004-1058 | ND |
| 2018-07-17 | 9590-007-0519 | ND |
| 2018-07-26 | 9553-006-0838 | ND |
| 2018-09-12 | 9590-004-0944 | ND |
| 2018-09-25 | 9553-006-0930 | ND |
| 2018-09-25 | 9553-004-0910 | ND |
| 2018-09-25 | 9553-008-0950 | ND |
| 2018-10-17 | 9553-007-0730 | ND |
| 2018-12-11 | 9553-004-0845 | ND |
| 2018-12-11 | 9553-006-0915 | ND |
| 2018-12-11 | 9553-008-1045 | ND |
| 2019-06-17 | 9553-008-1106 | ND |
| 2019-06-17 | 9553-007-0905 | ND |
| 2019-06-17 | 9553-006-1206 | ND |
| 2019-06-17 | 9553-004-0956 | ND |