Perchlorate
Middleborough Water Supply
Perchlorate, a component of rocket fuel, occurs both naturally and as a synthetic chemical. Ingested perchlorate interferes with thyroid function. Exposure to perchlorate during pregnancy and childhood can impair cognitive development. Read More.
According to the EPA, perchlorate likely contaminates the water of more than 16 million Americans. Perchlorate interferes with iodine uptake in the thyroid, which can result in reduced thyroid hormones and an impact on metabolism, physical development and cognitive development. Children and developing fetuses are the most at risk from perchlorate contamination.
Perchlorate is the only unregulated contaminant for which the EPA has attempted to set a federal drinking water standard since 1996. However, the agency has yet to propose a draft limit for this contaminant. Perchlorate in drinking water is regulated in Arizona, California, Massachusetts, New Jersey, New York and Texas. California set a public health goal of 1 part per billion for perchlorate in 2015.
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 | N/A | 0 | 0 | N/A |
| 2019 | 0.202 ppb | 9 | 9 | 0.0900 ppb - 0.290 ppb |
| 2020 | 0.273 ppb | 11 | 11 | 0.1000 ppb - 0.680 ppb |
| 2021 | 0.320 ppb | 9 | 9 | 0.140 ppb - 0.930 ppb |
| 2022 | 0.264 ppb | 9 | 9 | 0.110 ppb - 0.400 ppb |
| 2023 | 0.276 ppb | 9 | 9 | 0.0800 ppb - 0.430 ppb |
ppb = parts per billion
State, National, and Health Guidelines for Drinking Water
EWG Health Guideline: 1 ppb
The EWG Health Guideline of 1 ppb for perchlorate 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 hormone disruption.
ppb = parts per billion
All test results
| Date | Result |
|---|---|
| 2019-07-10 | 0.130 ppb |
| 2019-07-10 | 0.160 ppb |
| 2019-07-10 | 0.240 ppb |
| 2019-07-10 | 0.290 ppb |
| 2019-07-10 | 0.0900 ppb |
| 2019-07-10 | 0.260 ppb |
| 2019-07-10 | 0.260 ppb |
| 2019-07-10 | 0.200 ppb |
| 2019-07-19 | 0.190 ppb |
| 2020-04-17 | 0.280 ppb |
| 2020-07-15 | 0.280 ppb |
| 2020-07-15 | 0.120 ppb |
| 2020-07-15 | 0.220 ppb |
| 2020-07-15 | 0.180 ppb |
| 2020-07-15 | 0.370 ppb |
| 2020-07-15 | 0.1000 ppb |
| 2020-07-15 | 0.220 ppb |
| 2020-07-15 | 0.270 ppb |
| 2020-09-01 | 0.280 ppb |
| 2020-11-10 | 0.680 ppb |
| 2021-08-11 | 0.300 ppb |
| 2021-08-11 | 0.250 ppb |
| 2021-08-11 | 0.230 ppb |
| 2021-08-11 | 0.310 ppb |
| 2021-08-11 | 0.300 ppb |
| 2021-08-11 | 0.930 ppb |
| 2021-08-11 | 0.140 ppb |
| 2021-08-11 | 0.180 ppb |
| 2021-08-27 | 0.240 ppb |
| 2022-07-25 | 0.160 ppb |
| 2022-07-25 | 0.370 ppb |
| 2022-07-25 | 0.200 ppb |
| 2022-07-25 | 0.400 ppb |
| 2022-07-25 | 0.110 ppb |
| 2022-07-25 | 0.390 ppb |
| 2022-07-26 | 0.260 ppb |
| 2022-07-26 | 0.230 ppb |
| 2022-07-26 | 0.260 ppb |
| 2023-07-19 | 0.390 ppb |
| 2023-07-19 | 0.0800 ppb |
| 2023-07-19 | 0.230 ppb |
| 2023-07-19 | 0.220 ppb |
| 2023-08-04 | 0.250 ppb |
| 2023-08-04 | 0.430 ppb |
| 2023-08-04 | 0.220 ppb |
| 2023-08-04 | 0.250 ppb |
| 2023-08-04 | 0.410 ppb |