Nitrate
Norwalk City
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 |
|---|---|---|---|---|
| 2014 | 0.541 ppm | 12 | 12 | 0.230 ppm - 1.10 ppm |
| 2015 | 0.504 ppm | 12 | 10 | ND - 1.12 ppm |
| 2016 | 0.248 ppm | 12 | 5 | ND - 0.810 ppm |
| 2017 | 0.310 ppm | 12 | 7 | ND - 0.840 ppm |
| 2018 | 0.374 ppm | 12 | 11 | ND - 0.790 ppm |
| 2019 | 0.490 ppm | 10 | 10 | 0.170 ppm - 0.820 ppm |
ppm = parts per million
State and national drinking water standards and health guidelines
EWG Health Guideline 0.14 ppm
The EWG Health Guideline of 0.14 ppm for nitrate was defined by EWG . This health guideline protects against cancer and harm to fetal growth and development.
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 |
|---|---|---|
| 2014-01-15 | AG62884 | 0.610 ppm |
| 2014-02-12 | AG64524 | 0.730 ppm |
| 2014-03-05 | AG65768 | 0.780 ppm |
| 2014-04-02 | AG67508 | 0.760 ppm |
| 2014-05-07 | AG70041 | 1.10 ppm |
| 2014-06-04 | AG72190 | 0.280 ppm |
| 2014-07-02 | AG74561 | 0.230 ppm |
| 2014-08-06 | AG77082 | 0.730 ppm |
| 2014-09-03 | AG79537 | 0.450 ppm |
| 2014-10-08 | AG82469 | 0.280 ppm |
| 2014-11-05 | AG84394 | 0.240 ppm |
| 2014-12-03 | AG86460 | 0.300 ppm |
| 2015-01-07 | AG88645 | 0.270 ppm |
| 2015-02-04 | AG90153 | 0.600 ppm |
| 2015-03-04 | AG91760 | 0.970 ppm |
| 2015-04-01 | AG93591 | 1.12 ppm |
| 2015-05-13 | AG96407 | 0.700 ppm |
| 2015-06-03 | AG97778 | 0.700 ppm |
| 2015-07-08 | AH00610 | 0.710 ppm |
| 2015-08-05 | AH02699 | 0.240 ppm |
| 2015-09-02 | AH04987 | 0.340 ppm |
| 2015-10-07 | AH07447 | 0.400 ppm |
| 2015-11-04 | AH09317 | ND |
| 2015-12-02 | AH11125 | ND |
| 2016-01-06 | AH13089 | ND |
| 2016-02-03 | AH14724 | 0.460 ppm |
| 2016-03-02 | AH16437 | 0.810 ppm |
| 2016-04-06 | AH18799 | 0.690 ppm |
| 2016-05-04 | AH20801 | 0.560 ppm |
| 2016-06-08 | AH23381 | 0.460 ppm |
| 2016-07-13 | AH25927 | ND |
| 2016-08-03 | AH27389 | ND |
| 2016-09-07 | AH30110 | ND |
| 2016-10-05 | AH32792 | ND |
| 2016-11-02 | AH34981 | ND |
| 2016-12-07 | AH37625 | ND |
| 2017-01-11 | AH40302 | ND |
| 2017-02-01 | AH42069 | 0.410 ppm |
| 2017-03-01 | AH44130 | 0.800 ppm |
| 2017-04-05 | AH46503 | 0.790 ppm |
| 2017-05-03 | AH48833 | 0.840 ppm |
| 2017-06-07 | AH51408 | 0.330 ppm |
| 2017-07-05 | AH53781 | 0.210 ppm |
| 2017-08-02 | AH56154 | ND |
| 2017-09-06 | AH59049 | ND |
| 2017-10-04 | AH61408 | ND |
| 2017-11-08 | AH63906 | ND |
| 2017-12-06 | AH65866 | 0.340 ppm |
| 2018-01-03 | AH67429 | 0.240 ppm |
| 2018-02-14 | AH70126 | 0.790 ppm |
| 2018-03-06 | 18-13863-02 | 0.680 ppm |
| 2018-04-02 | 18-16500-04 | 0.550 ppm |
| 2018-05-01 | 18-17865-04 | 0.420 ppm |
| 2018-06-05 | 18-20677-06 | 0.420 ppm |
| 2018-07-10 | 18-23938-05 | ND |
| 2018-08-07 | 18-26412-04A | 0.170 ppm |
| 2018-09-04 | 18-28827-04A | 0.150 ppm |
| 2018-10-02 | 18-31424-05 | 0.300 ppm |
| 2018-11-06 | 18-341590-5 | 0.300 ppm |
| 2018-12-03 | 18-36103-05 | 0.470 ppm |
| 2019-01-07 | 19-10552-04A | 0.550 ppm |
| 2019-02-04 | 19-12317-04 | 0.820 ppm |
| 2019-03-04 | 19-14221-05 | 0.740 ppm |
| 2019-04-02 | 19-16345-04A | 0.630 ppm |
| 2019-05-06 | 19-19014-04A | 0.500 ppm |
| 2019-06-04 | 19-21157-05 | 0.390 ppm |
| 2019-07-01 | 19-23872-04A | 0.570 ppm |
| 2019-08-07 | 19-27050-04 | 0.170 ppm |
| 2019-09-03 | 19-29348-04A | 0.300 ppm |
| 2019-10-01 | 19-31924-04A | 0.230 ppm |