Know Your Environment. Protect Your Health.

Nitrate and nitrite

Norwalk First Taxing District

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.

 

6

Samples

0

Samples exceeding legal limit (MCL)

5

Samples exceeding
health guidelines

Testing results - average by year

 
YearAverage resultSamples takenDetectionsRange of results
20180.547 ppm110.547 ppm
20190.158 ppm110.158 ppm
20200.0490 ppm110.0490 ppm
20210.714 ppm110.714 ppm
20220.433 ppm110.433 ppm
20230.448 ppm110.448 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
2018-05-10214-13237NOX0.547 ppm
2019-09-24214-15434NOX0.158 ppm
2020-10-08214-17218NOX0.0490 ppm
2021-03-11214-17908NOX0.714 ppm
2022-04-21214-19948NOX0.433 ppm
2023-04-13214-21975NOX0.448 ppm