Nitrate and nitrite
South Norwalk Electric and Water
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 | 0.255 ppm | 2 | 2 | 0.240 ppm - 0.270 ppm |
| 2019 | 0.170 ppm | 2 | 2 | 0.150 ppm - 0.190 ppm |
| 2020 | 0.00500 ppm | 2 | 1 | ND - 0.01000 ppm |
| 2021 | 0.133 ppm | 2 | 2 | 0.124 ppm - 0.142 ppm |
| 2022 | ND | 2 | 0 | ND |
| 2023 | 0.0250 ppm | 2 | 2 | 0.0200 ppm - 0.0300 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 |
|---|---|---|
| 2018-05-10 | 18051007-NOX | 0.270 ppm |
| 2018-05-10 | 18051001-IOCR | 0.240 ppm |
| 2019-05-09 | 19050907-NOX | 0.190 ppm |
| 2019-05-09 | 19050901-IOCR | 0.150 ppm |
| 2020-05-14 | 20051407-NOX | 0.01000 ppm |
| 2020-05-14 | 20051401-IOCR | ND |
| 2021-05-13 | 21051307-NOX | 0.124 ppm |
| 2021-05-13 | 21051301-IOCR | 0.142 ppm |
| 2022-05-12 | 22051207-NOX | ND |
| 2022-05-12 | 22051201-IOCR | ND |
| 2023-05-17 | 23051707-NOX | 0.0300 ppm |
| 2023-05-17 | 23051701-IOCR | 0.0200 ppm |