Diquat
CTWC - Unionville System
NOTE: CTWC - Unionville System purchases water from Metropolitan District Commission which is required to test for diquat. Sample information shown below was taken by Metropolitan District Commission.
Diquat is a herbicide used on potato crops and aquatic weeds.
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: 6 ppb
The EWG Health Guideline of 6 ppb for diquat 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 cataracts.
EPA Maximum Contaminant
Level (MCL): 20 ppb
The legal limit for diquat, established in 1992, was based on a toxicity study in laboratory animals conducted in the 1980s.
ppb = parts per billion
All test results
NOTE: CTWC - Unionville System purchases water from Metropolitan District Commission which is required to test for diquat. 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 300107515 | ND |
| 2021-11-23 | S300107593 300107598 | ND |
| 2021-11-29 | S300109627 300109631 | ND |
| 2022-12-15 | S300287039 300287046 | ND |
| 2022-12-15 | S300287062 300287067 | ND |
| 2022-12-15 | S300287090 300287095 | ND |
| 2023-12-05 | S300456329 300456334 | ND |
| 2023-12-06 | S300456308 300456313 | ND |
| 2023-12-06 | S300456298 300456303 | ND |