Nitrate and nitrite
Connecticut Water Company - Northern Region-Western System
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 | 2.13 ppm | 13 | 13 | 0.150 ppm - 4.38 ppm |
| 2019 | 2.33 ppm | 12 | 12 | 0.176 ppm - 4.42 ppm |
| 2020 | 2.88 ppm | 16 | 16 | 0.1000 ppm - 10.1 ppm |
| 2021 | 2.06 ppm | 12 | 12 | 0.145 ppm - 4.04 ppm |
| 2022 | 2.09 ppm | 17 | 17 | 0.150 ppm - 4.33 ppm |
| 2023 | 1.89 ppm | 14 | 14 | 0.0800 ppm - 4.04 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 |
|---|---|---|
| 2018-01-12 | BZ72527NOX | 4.38 ppm |
| 2018-01-12 | BZ72529NOX | 1.66 ppm |
| 2018-01-12 | BZ72528NOX | 0.740 ppm |
| 2018-01-23 | BZ78886NOX | 0.150 ppm |
| 2018-01-23 | BZ78887NOX | 0.150 ppm |
| 2018-01-31 | BZ82949NOX | 3.55 ppm |
| 2018-01-31 | BZ82691IOCR | 0.180 ppm |
| 2018-03-02 | BZ97488NOX | 1.54 ppm |
| 2018-04-19 | CA23517NOX | 3.22 ppm |
| 2018-07-12 | CA89150 | 2.19 ppm |
| 2018-07-13 | CA89903 | 2.82 ppm |
| 2018-07-20 | CA94720 | 4.25 ppm |
| 2018-12-10 | NOX 200515418 | 2.84 ppm |
| 2019-01-02 | NOX 200517305 | 0.176 ppm |
| 2019-01-10 | IOCR 200518412 | 0.209 ppm |
| 2019-01-15 | NOX 200518779 | 0.224 ppm |
| 2019-03-15 | NOX 200524883 | 0.439 ppm |
| 2019-03-22 | NOX 200525613 | 2.16 ppm |
| 2019-03-22 | NOX 200525612 | 3.92 ppm |
| 2019-05-30 | NOX 200534244 | 4.42 ppm |
| 2019-05-30 | NOX 200534243 | 3.10 ppm |
| 2019-07-02 | NOX 200538771 | 2.72 ppm |
| 2019-07-02 | NOX 200538782 | 4.34 ppm |
| 2019-07-18 | NOX 200541147 | 2.27 ppm |
| 2019-10-03 | NOX 200551371 | 4.02 ppm |
| 2020-01-02 | NOX 200561503 | 0.125 ppm |
| 2020-01-09 | NOX 200562368 | 0.139 ppm |
| 2020-01-15 | IOCR 200563111 | 0.162 ppm |
| 2020-03-24 | NOX 200570369 | 3.12 ppm |
| 2020-06-10 | NOX 200578804 | 3.37 ppm |
| 2020-06-24 | 200580453 | 0.1000 ppm |
| 2020-08-12 | 200586387 | 10.1 ppm |
| 2020-08-12 | NOX 200586388 | 3.85 ppm |
| 2020-08-14 | CG54062 | 9.28 ppm |
| 2020-09-09 | NOX 200589664 | 2.02 ppm |
| 2020-09-14 | NOX 200590110 | 2.47 ppm |
| 2020-09-14 | NOX 200590117 | 0.630 ppm |
| 2020-09-14 | NOX 200590123 | 2.17 ppm |
| 2020-09-14 | NOX 200590125 | 1.87 ppm |
| 2020-09-14 | NOX 200590114 | 2.86 ppm |
| 2020-10-07 | NOX 200593169 | 3.82 ppm |
| 2021-01-07 | NOX 200603066 | 4.04 ppm |
| 2021-02-17 | NOX 200607103 | 0.150 ppm |
| 2021-03-05 | IOCR 200608709 | 0.145 ppm |
| 2021-03-05 | NOX 200608709 | 0.145 ppm |
| 2021-04-12 | NOX 200612731 | 3.46 ppm |
| 2021-06-07 | NOX 200619842 | 2.19 ppm |
| 2021-06-07 | NOX 200619843 | 2.99 ppm |
| 2021-06-07 | NOX 200621422 | 2.90 ppm |
| 2021-07-07 | NOX 200623599 | 3.97 ppm |
| 2021-09-14 | 300059920 300059921 | 1.86 ppm |
| 2021-09-14 | 300059931 300059933 | 0.598 ppm |
| 2021-10-05 | N300075495 300075496 | 2.26 ppm |
| 2022-01-12 | CK15030 | 3.39 ppm |
| 2022-01-12 | CK15031 | 0.470 ppm |
| 2022-01-12 | CK15027 | 1.83 ppm |
| 2022-01-24 | CK22294 | 0.610 ppm |
| 2022-01-25 | CK23181 | 0.150 ppm |
| 2022-01-25 | CK23176 | 2.99 ppm |
| 2022-02-01 | CK27430 | 0.190 ppm |
| 2022-02-01 | CK27434 | 0.170 ppm |
| 2022-02-16 | CK69357 | 3.03 ppm |
| 2022-02-16 | CK69358 | 2.94 ppm |
| 2022-06-08 | CL52210 | 3.01 ppm |
| 2022-06-14 | CL56640 | 2.39 ppm |
| 2022-06-15 | CL58007 | 4.08 ppm |
| 2022-07-11 | CL74895 | 3.81 ppm |
| 2022-09-08 | CM25672 | 0.170 ppm |
| 2022-09-20 | CM37295 | 1.99 ppm |
| 2022-11-03 | CM76613 | 4.33 ppm |
| 2023-01-10 | CN19735 | 0.0800 ppm |
| 2023-01-10 | CN20742 | 3.10 ppm |
| 2023-01-11 | CN20957 | 0.1000 ppm |
| 2023-01-18 | CN25096 | 0.140 ppm |
| 2023-02-01 | CN33443 | 0.140 ppm |
| 2023-02-22 | CN47995 | 0.450 ppm |
| 2023-02-22 | CN47869 | 2.82 ppm |
| 2023-04-03 | CN74709 | 1.92 ppm |
| 2023-04-11 | CN81219 | 3.11 ppm |
| 2023-05-22 | CO11671 | 3.19 ppm |
| 2023-07-05 | CO43797 | 4.04 ppm |
| 2023-10-04 | CP17834 | 3.88 ppm |
| 2023-10-31 | CP38331 | 1.40 ppm |
| 2023-12-13 | CP67269 | 2.13 ppm |