Nitrate and nitrite
CTWC - Shoreline Region-Guilford 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 | 0.764 ppm | 16 | 16 | 0.0250 ppm - 2.71 ppm |
| 2019 | 0.465 ppm | 24 | 24 | 0.0150 ppm - 3.37 ppm |
| 2020 | 0.648 ppm | 25 | 25 | 0.0120 ppm - 1.98 ppm |
| 2021 | 0.552 ppm | 20 | 20 | 0.0190 ppm - 2.51 ppm |
| 2022 | 0.468 ppm | 22 | 21 | ND - 2.74 ppm |
| 2023 | 0.761 ppm | 26 | 24 | ND - 2.95 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 |
|---|---|---|
| 2018-01-16 | BZ73475NOX | 0.280 ppm |
| 2018-03-30 | CA11466NOX | 0.170 ppm |
| 2018-03-30 | CA11463IOCR | 0.150 ppm |
| 2018-06-04 | CA63507NOX | 0.200 ppm |
| 2018-06-13 | CA69714NOX | 0.0500 ppm |
| 2018-06-13 | CA69718NOX | 2.71 ppm |
| 2018-06-13 | CA69716NOX | 1.01 ppm |
| 2018-06-13 | CA69715NOX | 2.17 ppm |
| 2018-06-13 | CA69717NOX | 1.76 ppm |
| 2018-06-20 | CA75544NOX | 0.260 ppm |
| 2018-09-19 | NOX 200506169 | 0.125 ppm |
| 2018-10-09 | NOX 200508367 | 0.124 ppm |
| 2018-11-08 | NOX 200512198 | 0.0250 ppm |
| 2018-11-21 | NOX 200513547 | 1.50 ppm |
| 2018-11-26 | NOX 200513931 | 1.60 ppm |
| 2018-12-10 | NOX 200515324 | 0.0780 ppm |
| 2019-01-07 | NOX 200517748 | 0.118 ppm |
| 2019-01-30 | NOX 200520057 | 0.123 ppm |
| 2019-02-06 | NOX 200520859 | 0.155 ppm |
| 2019-02-07 | NOX 200521039 | 0.159 ppm |
| 2019-02-27 | IOCR 200523002 | 0.112 ppm |
| 2019-03-05 | NOX 200523518 | 0.126 ppm |
| 2019-04-02 | NOX 200526702 | 0.108 ppm |
| 2019-04-08 | NOX 200527439 | 0.101 ppm |
| 2019-05-06 | NOX 200530919 | 0.0480 ppm |
| 2019-06-05 | NOX 200535054 | 0.0620 ppm |
| 2019-06-24 | NOX 200537625 | 0.0150 ppm |
| 2019-07-09 | NOX 200539960 | 0.123 ppm |
| 2019-07-10 | NOX 200539996 | 0.426 ppm |
| 2019-07-10 | NOX 200539998 | 0.426 ppm |
| 2019-07-16 | NOX 200541091 | 3.37 ppm |
| 2019-07-16 | NOX 200540648 | 0.924 ppm |
| 2019-07-16 | NOX 200540644 | 2.13 ppm |
| 2019-08-05 | NOX 200545065 | 0.0740 ppm |
| 2019-09-11 | NOX 200548435 | 0.0400 ppm |
| 2019-09-17 | NOX 200549238 | 1.02 ppm |
| 2019-09-18 | NOX 200549465 | 1.33 ppm |
| 2019-10-02 | NOX 200551087 | 0.0260 ppm |
| 2019-11-12 | NOX 200556637 | 0.0620 ppm |
| 2019-12-05 | NOX 200559108 | 0.0980 ppm |
| 2020-01-09 | NOX 200562365 | 0.164 ppm |
| 2020-01-20 | NOX 200563509 | 1.36 ppm |
| 2020-01-20 | NOX 200563521 | 1.38 ppm |
| 2020-01-21 | NOX 200563499 | 0.0190 ppm |
| 2020-01-21 | NOX 200563515 | 1.89 ppm |
| 2020-01-21 | NOX 200563516 | 1.91 ppm |
| 2020-01-28 | NOX 200564211 | 1.98 ppm |
| 2020-01-28 | NOX 200564212 | 1.97 ppm |
| 2020-02-10 | NOX 200565531 | 0.158 ppm |
| 2020-02-11 | NOX 200565799 | 0.154 ppm |
| 2020-02-11 | NOX 200565797 | 0.139 ppm |
| 2020-02-11 | IOCR 200565797 | 0.139 ppm |
| 2020-02-25 | NOX 200567275 | 1.60 ppm |
| 2020-02-25 | NOX 200567276 | 1.59 ppm |
| 2020-03-03 | NOX 200567975 | 0.138 ppm |
| 2020-04-06 | NOX 200572489 | 0.101 ppm |
| 2020-05-05 | NOX 200574587 | 0.0740 ppm |
| 2020-06-02 | NOX 200577714 | 0.0720 ppm |
| 2020-07-08 | NOX 200582000 | 0.0810 ppm |
| 2020-07-13 | NOX 200582477 | 1.11 ppm |
| 2020-08-12 | NOX 200586368 | 0.0120 ppm |
| 2020-09-15 | NOX 200590367 | 0.0220 ppm |
| 2020-10-21 | NOX 200595066 | 0.0160 ppm |
| 2020-11-02 | NOX 200596424 | 0.0220 ppm |
| 2020-12-09 | NOX 200600816 | 0.118 ppm |
| 2021-01-05 | NOX 200602753 | 1.45 ppm |
| 2021-01-06 | NOX 200602994 | 0.0410 ppm |
| 2021-01-11 | NOX 200603457 | 0.217 ppm |
| 2021-01-25 | NOX 200604768 | 1.53 ppm |
| 2021-02-17 | NOX 200607136 | 0.253 ppm |
| 2021-03-01 | NOX 200608135 | 0.197 ppm |
| 2021-04-20 | NOX 200613997 | 0.0570 ppm |
| 2021-05-12 | NOX 200616876 | 0.0450 ppm |
| 2021-06-02 | NOX 200619284 | 0.0420 ppm |
| 2021-06-29 | NOX 200622710 | 2.19 ppm |
| 2021-07-01 | NOX 200622841 | 0.0550 ppm |
| 2021-07-07 | NOX 200623650 | 0.965 ppm |
| 2021-07-20 | NOX 200625447 | 2.51 ppm |
| 2021-08-09 | NOX 200627644 | 0.0480 ppm |
| 2021-09-21 | 300064946 300064949 | 0.0780 ppm |
| 2021-09-30 | R300072099 300072101 | 0.0460 ppm |
| 2021-10-04 | N300073657 300073660 | 0.0620 ppm |
| 2021-11-01 | N300093127 300093130 | 0.0190 ppm |
| 2021-11-15 | N300102725 300102726 | 1.15 ppm |
| 2021-12-08 | N300115259 300115262 | 0.0860 ppm |
| 2022-01-11 | CK14095 | 1.11 ppm |
| 2022-01-11 | CK14105 | 2.01 ppm |
| 2022-01-27 | CK24307 | 0.170 ppm |
| 2022-02-15 | CK68298 | 0.150 ppm |
| 2022-02-28 | CK76192 | 0.01000 ppm |
| 2022-03-07 | CK80900 | 1.04 ppm |
| 2022-03-28 | CK96121 | 0.0900 ppm |
| 2022-04-25 | CL16306 | 0.0400 ppm |
| 2022-05-11 | CL27611 | 0.0400 ppm |
| 2022-06-06 | CL49387 | 0.0700 ppm |
| 2022-06-14 | CL56476 | 2.74 ppm |
| 2022-07-20 | CL83807 | 0.0300 ppm |
| 2022-08-15 | CM05635 | 1.37 ppm |
| 2022-08-15 | CM05636 | 1.10 ppm |
| 2022-08-24 | CM14827 | 0.0700 ppm |
| 2022-08-29 | CM17830 | 0.0300 ppm |
| 2022-08-29 | CM17831 | 0.0200 ppm |
| 2022-09-28 | CM43103 | 0.0500 ppm |
| 2022-10-04 | CM49564 | 0.0300 ppm |
| 2022-11-02 | CM75295 | ND |
| 2022-12-01 | CM94640 | 0.0400 ppm |
| 2022-12-01 | CM94644 | 0.0800 ppm |
| 2023-01-04 | CN17497 | 2.02 ppm |
| 2023-01-05 | CN17020 | 0.170 ppm |
| 2023-01-09 | CN19603 | 2.03 ppm |
| 2023-01-10 | CN20798 | 1.33 ppm |
| 2023-02-08 | CN39378 | 0.190 ppm |
| 2023-02-13 | CN41858 | 0.120 ppm |
| 2023-02-13 | CN41859 | 0.160 ppm |
| 2023-03-13 | CN59172 | 0.130 ppm |
| 2023-04-05 | CN77492 | 0.0900 ppm |
| 2023-05-10 | CO03350 | 0.0600 ppm |
| 2023-06-05 | CO19978 | 0.0700 ppm |
| 2023-06-13 | CO27277 | 0.930 ppm |
| 2023-08-10 | CO71352 | 0.0900 ppm |
| 2023-08-28 | CO85102 | 0.110 ppm |
| 2023-09-05 | CO90692 | 0.1000 ppm |
| 2023-09-12 | CO95874 | 2.45 ppm |
| 2023-09-12 | CO95875 | 0.540 ppm |
| 2023-09-12 | CO95877 | 1.82 ppm |
| 2023-10-12 | CP23629 | 1.31 ppm |
| 2023-10-23 | CP31868 | 0.0700 ppm |
| 2023-11-06 | CP42068 | 0.0300 ppm |
| 2023-11-28 | CP55321 | ND |
| 2023-11-28 | CP55320 | ND |
| 2023-11-29 | CP56432 | 2.90 ppm |
| 2023-11-29 | CP56434 | 2.95 ppm |
| 2023-12-04 | CP59688 | 0.110 ppm |