Heptachlor epoxide
CTWC - Unionville System
NOTE: CTWC - Unionville System purchases water from Metropolitan District Commission which is required to test for heptachlor epoxide. Sample information shown below was taken by Metropolitan District Commission.
Heptachlor epoxide is a breakdown product of heptachlor, a highly toxic and carcinogenic pesticide banned in the U.S. since the 1980s.
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 | ND | 7 | 0 | ND |
| 2019 | ND | 12 | 0 | ND |
| 2020 | ND | 3 | 0 | ND |
| 2021 | ND | 3 | 0 | ND |
| 2022 | ND | 6 | 0 | ND |
| 2023 | ND | 3 | 0 | ND |
ppb = parts per billion
State, National, and Health Guidelines for Drinking Water
EWG Health Guideline: 0.006 ppb
The EWG Health Guideline of 0.006 ppb for heptachlor epoxide 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): 0.2 ppb
The legal limit for heptachlor epoxide, established in 1991, 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.
ppb = parts per billion
All test results
NOTE: CTWC - Unionville System purchases water from Metropolitan District Commission which is required to test for heptachlor epoxide. Sample information shown below was taken by Metropolitan District Commission.
| Date | Lab ID | Result |
|---|---|---|
| 2018-06-27 | CA79476 | ND |
| 2018-06-27 | CA79477 | ND |
| 2018-06-27 | CA79475 | ND |
| 2018-09-25 | CB38504 | ND |
| 2018-09-25 | CB38505R | ND |
| 2018-09-25 | CB38869 | ND |
| 2018-09-25 | CB38505 | ND |
| 2020-12-08 | SOC 200600638 | ND |
| 2020-12-08 | SOC 200600609 | ND |
| 2020-12-09 | SOC 200600592 | ND |
| 2021-11-23 | S300107511 300107513 | ND |
| 2021-11-23 | S300107593 300107596 | ND |
| 2021-11-29 | S300109627 300109629 | ND |
| 2022-12-15 | S300287039 300287044 | ND |
| 2022-12-15 | S300287062 300287065 | ND |
| 2022-12-15 | S300287090 300287093 | ND |
| 2023-12-05 | S300456329 300456332 | ND |
| 2023-12-06 | S300456308 300456311 | ND |
| 2023-12-06 | S300456298 300456301 | ND |