Nitrate and nitrite
Westerly Water Department
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.
41
Samples
0
Samples exceeding legal limit (MCL)
41
Samples exceeding
health guidelines
Testing results - average by year
| Year | Average result | Samples taken | Detections | Range of results |
|---|---|---|---|---|
| 2014 | 1.30 ppm | 12 | 12 | 0.180 ppm - 2.50 ppm |
| 2015 | 1.29 ppm | 6 | 6 | 0.170 ppm - 2.62 ppm |
| 2016 | N/A | 0 | 0 | N/A |
| 2017 | 1.20 ppm | 12 | 12 | 0.210 ppm - 2.73 ppm |
| 2018 | 2.15 ppm | 1 | 1 | 2.15 ppm |
| 2019 | 1.58 ppm | 10 | 10 | 0.210 ppm - 3.39 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 |
|---|---|---|
| 2014-05-01 | BG39530-IOC | 1.01 ppm |
| 2014-05-01 | BG39529-IOC | 0.960 ppm |
| 2014-05-01 | BG39528-IOC | 2.47 ppm |
| 2014-05-02 | BG40111-IOC | 1.69 ppm |
| 2014-05-02 | BG40109-IOC | 1.000 ppm |
| 2014-05-06 | BG41004-IOC | 1.44 ppm |
| 2014-05-08 | BG42439-IOC | 1.50 ppm |
| 2014-05-13 | BG43968-IOC | 2.50 ppm |
| 2014-05-13 | BG43969-IOC | 0.910 ppm |
| 2014-05-14 | BG44525-IOC | 0.690 ppm |
| 2014-05-15 | BG45214-IOC | 0.180 ppm |
| 2014-05-15 | BG45216_IOC | 1.28 ppm |
| 2015-03-13 | BH83396_WL16_WL5 | 0.750 ppm |
| 2015-03-13 | BH83407_WL16_WL5 | 2.62 ppm |
| 2015-03-13 | BH83397_WL16_WL5 | 1.57 ppm |
| 2015-03-13 | BH83394_WL16_WL5 | 0.170 ppm |
| 2015-03-13 | BH83395_WL16_WL5 | 1.42 ppm |
| 2015-03-24 | BH87234_WL16_WL5 | 1.18 ppm |
| 2017-02-14 | BX60459_WL16_WL5 | 2.73 ppm |
| 2017-02-14 | BX60462_WL16_WL5 | 1.32 ppm |
| 2017-02-14 | BX60460_WL16_WL5 | 1.13 ppm |
| 2017-02-14 | BX60461_WL16_WL5 | 0.990 ppm |
| 2017-02-14 | BX60463_WL16_WL5 | 1.26 ppm |
| 2017-02-15 | BX63397_WL16_WL5 | 0.840 ppm |
| 2017-02-15 | BX63398_WL16_WL5 | 1.32 ppm |
| 2017-02-15 | BX63399_WL16_WL5 | 0.210 ppm |
| 2017-02-16 | BX69880_WL16_WL5 | 1.86 ppm |
| 2017-02-16 | BX69879_WL16_WL5 | 0.540 ppm |
| 2017-02-16 | BX69881_WL16_WL5 | 0.570 ppm |
| 2017-02-16 | BX69882_WL16_WL5 | 1.61 ppm |
| 2018-04-27 | CA37843_WL16_WL5 | 2.15 ppm |
| 2019-03-04 | CC61974_WL16_WL5 | 1.22 ppm |
| 2019-03-04 | CC61976_WL16_WL5 | 3.39 ppm |
| 2019-03-04 | CC61975_WL16_WL5 | 2.17 ppm |
| 2019-03-04 | CC61973_WL16_WL5 | 1.000 ppm |
| 2019-03-04 | CC61972_WL16_WL5 | 2.57 ppm |
| 2019-03-04 | CC61977_WL16_WL5 | 0.630 ppm |
| 2019-03-04 | CC61978_WL16_WL5 | 1.40 ppm |
| 2019-03-06 | CC62791_WL16_WL5 | 1.41 ppm |
| 2019-03-06 | CC62789_WL16_WL5 | 1.80 ppm |
| 2019-03-06 | CC62790_WL16_WL5 | 0.210 ppm |