Nitrate
Redmond Water Department
Nitrate, a fertilizer chemical, frequently contaminates drinking water due to agricultural and urban runoff, and discharges from municipal wastewater treatment plants and septic tanks. Excessive nitrate in water can cause oxygen deprivation in infants and increase the risk of cancer. 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 | 1.25 ppm | 7 | 7 | 0.180 ppm - 4.43 ppm |
| 2019 | 0.534 ppm | 7 | 7 | 0.180 ppm - 1.73 ppm |
| 2020 | 1.07 ppm | 7 | 7 | 0.190 ppm - 4.32 ppm |
| 2021 | 0.568 ppm | 8 | 8 | 0.180 ppm - 1.61 ppm |
| 2022 | 0.675 ppm | 8 | 8 | 0.200 ppm - 2.42 ppm |
| 2023 | 0.684 ppm | 8 | 8 | 0.200 ppm - 2.64 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
The legal limit for nitrate, established in 1962, was developed to protect infants from acute methemoglobinemia, a life-threatening disorder of oxygen transport in the body. This limit does not fully protect against the risk of cancer and harm to the developing fetus.
ppm = parts per million
All test results
| Date | Lab ID | Result |
|---|---|---|
| 2018-06-19 | 1845000-I | 0.490 ppm |
| 2018-06-19 | 1845023-I | 0.210 ppm |
| 2018-06-19 | 1845041-I | 0.500 ppm |
| 2018-06-19 | 1844961-I | 0.300 ppm |
| 2018-07-17 | 18-52530-I | 0.180 ppm |
| 2018-10-25 | 1881935-I | 4.43 ppm |
| 2018-10-25 | 1881936-I | 2.64 ppm |
| 2019-07-30 | 1954940-I | 0.320 ppm |
| 2019-07-30 | 1954941-I | 0.270 ppm |
| 2019-07-30 | 1954942-I | 0.580 ppm |
| 2019-07-30 | 1954943-I | 0.190 ppm |
| 2019-07-30 | 1954944-I | 0.180 ppm |
| 2019-07-30 | 1954945-I | 0.470 ppm |
| 2019-10-15 | 1976815-I | 1.73 ppm |
| 2020-07-22 | 2046682-I | 0.290 ppm |
| 2020-07-22 | 2046681-I | 1.56 ppm |
| 2020-07-22 | 2046680-I | 4.32 ppm |
| 2020-07-22 | 2046684-I | 0.190 ppm |
| 2020-07-22 | 2046683-I | 0.500 ppm |
| 2020-07-22 | 2046685-I | 0.190 ppm |
| 2020-07-22 | 2046686-I | 0.470 ppm |
| 2021-05-11 | 2132295-I | 0.290 ppm |
| 2021-05-11 | 2132299-I | 0.490 ppm |
| 2021-05-11 | 2132264 | 0.540 ppm |
| 2021-05-18 | 2133712-I | 0.180 ppm |
| 2021-05-18 | 2133726-I | 0.460 ppm |
| 2021-05-18 | 2133715-I | 0.190 ppm |
| 2021-06-02 | 2137359-I | 1.61 ppm |
| 2021-06-02 | 2137357-I | 0.780 ppm |
| 2022-08-10 | 22-51472 | 0.200 ppm |
| 2022-08-10 | 22-51436-I | 0.530 ppm |
| 2022-08-10 | 22-51475 | 0.530 ppm |
| 2022-08-10 | 22-51468-I | 0.530 ppm |
| 2022-08-10 | 22-51469-I | 0.210 ppm |
| 2022-08-17 | 22-53228 | 0.680 ppm |
| 2022-08-17 | 22-53230-I | 0.300 ppm |
| 2022-08-17 | 22-53226 | 2.42 ppm |
| 2023-07-13 | 23-40887 | 0.480 ppm |
| 2023-07-13 | 23-40885-I | 0.200 ppm |
| 2023-07-13 | 23-40863-I | 2.64 ppm |
| 2023-07-13 | 23-40882 | 0.310 ppm |
| 2023-07-13 | 23-40883-I | 0.500 ppm |
| 2023-07-13 | 23-40886-I | 0.510 ppm |
| 2023-07-13 | 23-40884-I | 0.200 ppm |
| 2023-07-17 | 23-41527-I | 0.630 ppm |