Nitrate and nitrite
North Castle Water District #4
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 | 0.560 ppm | 2 | 2 | 0.181 ppm - 0.939 ppm |
| 2019 | 0.713 ppm | 2 | 2 | 0.145 ppm - 1.28 ppm |
| 2020 | 0.500 ppm | 2 | 1 | ND - 1.000 ppm |
| 2021 | 0.835 ppm | 2 | 2 | 0.129 ppm - 1.54 ppm |
| 2022 | 0.828 ppm | 2 | 2 | 0.106 ppm - 1.55 ppm |
| 2023 | 0.438 ppm | 6 | 6 | 0.0796 ppm - 1.38 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 | AU15716-INT | 0.181 ppm |
| 2018-07-24 | AU15718-NIT | 0.939 ppm |
| 2019-08-05 | AV16474-NIT | 0.145 ppm |
| 2019-08-05 | AV16471-NIT | 1.28 ppm |
| 2020-07-29 | AW14499-NIT | 1.000 ppm |
| 2020-08-27 | AW16635-NIT | ND |
| 2021-08-03 | AX15556-NIT | 1.54 ppm |
| 2021-08-03 | AX15569-NIT | 0.129 ppm |
| 2022-07-20 | AY12624-NIT | 1.55 ppm |
| 2022-07-21 | AY12753-NIT | 0.106 ppm |
| 2023-03-21 | AZ05017-NIT | 0.113 ppm |
| 2023-03-21 | AZ05015-NIT | 0.116 ppm |
| 2023-03-22 | AZ05102-NIT | 1.38 ppm |
| 2023-07-10 | AZ12341-NIT | 0.0796 ppm |
| 2023-07-10 | AZ12342-NIT | 0.745 ppm |
| 2023-07-25 | AZ13469-NIT | 0.194 ppm |