Nitrate and nitrite
North Castle Water District #1
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 | 0.146 ppm | 1 | 1 | 0.146 ppm |
| 2019 | 0.214 ppm | 1 | 1 | 0.214 ppm |
| 2020 | ND | 1 | 0 | ND |
| 2021 | 0.169 ppm | 1 | 1 | 0.169 ppm |
| 2022 | 0.172 ppm | 1 | 1 | 0.172 ppm |
| 2023 | 0.165 ppm | 4 | 4 | 0.143 ppm - 0.202 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 |
|---|---|---|
| 2018-07-24 | AU15717-NIT | 0.146 ppm |
| 2019-08-05 | AV16472-NIT | 0.214 ppm |
| 2020-07-29 | AW14502-NIT | ND |
| 2021-08-04 | AX15703-NIT | 0.169 ppm |
| 2022-07-12 | AY12751-NIT | 0.172 ppm |
| 2023-03-22 | AZ05098-NIT | 0.154 ppm |
| 2023-03-22 | AZ05100-NIT | 0.143 ppm |
| 2023-07-10 | AZ12338-NIT | 0.161 ppm |
| 2023-07-25 | AZ13471-NIT | 0.202 ppm |