Nitrate and nitrite
Block Island Water Company
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.
16
Samples
0
Samples exceeding legal limit (MCL)
6
Samples exceeding
health guidelines
Testing results - average by year
| Year | Average result | Samples taken | Detections | Range of results |
|---|---|---|---|---|
| 2014 | 0.0507 ppm | 3 | 1 | ND - 0.152 ppm |
| 2015 | 0.155 ppm | 5 | 3 | ND - 0.418 ppm |
| 2016 | 0.203 ppm | 2 | 2 | 0.120 ppm - 0.285 ppm |
| 2017 | 0.0538 ppm | 4 | 2 | ND - 0.208 ppm |
| 2018 | N/A | 0 | 0 | N/A |
| 2019 | 0.195 ppm | 2 | 1 | ND - 0.390 ppm |
ppm = parts per million
State and national drinking water standards and health guidelines
EWG Health Guideline 0.14 ppm
The 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 |
|---|---|---|
| 2014-04-09 | 1404248-02I | ND |
| 2014-04-09 | 1404248-01I | 0.152 ppm |
| 2014-09-10 | 1409222-01_IOC | ND |
| 2015-05-13 | 1505347-06I | 0.245 ppm |
| 2015-05-13 | 1505347-05I | 0.111 ppm |
| 2015-05-13 | 1505347-03I | ND |
| 2015-05-13 | 1505347-04I | ND |
| 2015-05-13 | 1505347-02I | 0.418 ppm |
| 2016-04-20 | 1604606-06I | 0.285 ppm |
| 2016-04-20 | 1604606-05I | 0.120 ppm |
| 2017-04-06 | 1704183-05I | 0.208 ppm |
| 2017-04-06 | 1704183-04I | ND |
| 2017-04-06 | 1704183-03I | 0.00700 ppm |
| 2017-07-09 | C707069-01 N | ND |
| 2019-04-10 | 1904-06459-002 | ND |
| 2019-04-10 | 1904-06459-001 | 0.390 ppm |