Nitrate and nitrite
Aquarion Water Company of Connecticut - Greenwich System
Nitrate and nitrite enter water from fertilizer runoff, septic tanks and urban runoff. These contaminants can cause oxygen deprivation for infants and increase the risk of cancer. Nitrite is significantly more toxic than nitrate. Click here to read more about nitrate.
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 | 0.320 ppm | 5 | 5 | 0.291 ppm - 0.346 ppm |
| 2019 | 0.304 ppm | 4 | 4 | 0.126 ppm - 0.499 ppm |
| 2020 | 0.223 ppm | 4 | 4 | 0.104 ppm - 0.337 ppm |
| 2021 | 0.318 ppm | 4 | 4 | 0.235 ppm - 0.402 ppm |
| 2022 | 0.0973 ppm | 4 | 2 | ND - 0.314 ppm |
| 2023 | 0.142 ppm | 4 | 2 | ND - 0.442 ppm |
ppm = parts per million
State, National, and Health Guidelines for Drinking Water
EWG Health Guideline: 0.14 ppm
The EWG health guideline of 0.14 parts per million, or ppm, for nitrate and nitrite is based on the equivalent health guideline for nitrate, as defined in a peer-reviewed scientific study by EWG. This guideline represents a one-in-one-million annual cancer risk level.
EPA Maximum Contaminant
Level (MCL): 10 ppm
ppm = parts per million
All test results
| Date | Lab ID | Result |
|---|---|---|
| 2018-04-02 | 201803870-NOX | 0.326 ppm |
| 2018-04-02 | 201803870-IOCR | 0.326 ppm |
| 2018-04-02 | 201803873-NOX | 0.312 ppm |
| 2018-10-01 | 201815017-NOX | 0.291 ppm |
| 2018-10-01 | 201815016-IOCR | 0.346 ppm |
| 2019-04-01 | 201904114-NOX | 0.132 ppm |
| 2019-04-01 | 201904109-NOX | 0.499 ppm |
| 2019-04-01 | 201904111-IOCR | 0.126 ppm |
| 2019-04-01 | 201904110-IOCR | 0.458 ppm |
| 2020-04-06 | 202004726-NOX | 0.337 ppm |
| 2020-04-06 | 202004727-IOCR | 0.335 ppm |
| 2020-04-07 | 202004857-IOCR | 0.104 ppm |
| 2020-04-07 | 202004860-NOX | 0.114 ppm |
| 2021-04-05 | 202104315-NOX | 0.258 ppm |
| 2021-04-05 | 202104312-IOCR | 0.235 ppm |
| 2021-05-10 | 202106584-NOX | 0.402 ppm |
| 2021-05-10 | 202106585-IOCR | 0.377 ppm |
| 2022-04-05 | 202204953-NOX | 0.0750 ppm |
| 2022-04-05 | 202204950-IOCR | ND |
| 2022-05-16 | 202207710-NOX | 0.314 ppm |
| 2022-05-16 | 202207707-IOCR | ND |
| 2023-04-03 | 202304838-NOX | 0.126 ppm |
| 2023-04-03 | 202304835-IOCR | ND |
| 2023-06-06 | 202309335-NOX | 0.442 ppm |
| 2023-06-06 | 202309336-IOCR | ND |