Know Your Environment. Protect Your Health.

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.

 

84

Samples

1

Samples exceeding legal limit (MCL)

77

Samples exceeding
health guidelines

Testing results - average by year

 
YearAverage resultSamples takenDetectionsRange of results
20182.13 ppm13130.150 ppm - 4.38 ppm
20192.33 ppm12120.176 ppm - 4.42 ppm
20202.88 ppm16160.1000 ppm - 10.1 ppm
20212.06 ppm12120.145 ppm - 4.04 ppm
20222.09 ppm17170.150 ppm - 4.33 ppm
20231.89 ppm14140.0800 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
2018-01-12BZ72527NOX4.38 ppm
2018-01-12BZ72529NOX1.66 ppm
2018-01-12BZ72528NOX0.740 ppm
2018-01-23BZ78886NOX0.150 ppm
2018-01-23BZ78887NOX0.150 ppm
2018-01-31BZ82949NOX3.55 ppm
2018-01-31BZ82691IOCR0.180 ppm
2018-03-02BZ97488NOX1.54 ppm
2018-04-19CA23517NOX3.22 ppm
2018-07-12CA891502.19 ppm
2018-07-13CA899032.82 ppm
2018-07-20CA947204.25 ppm
2018-12-10NOX 2005154182.84 ppm
2019-01-02NOX 2005173050.176 ppm
2019-01-10IOCR 2005184120.209 ppm
2019-01-15NOX 2005187790.224 ppm
2019-03-15NOX 2005248830.439 ppm
2019-03-22NOX 2005256132.16 ppm
2019-03-22NOX 2005256123.92 ppm
2019-05-30NOX 2005342444.42 ppm
2019-05-30NOX 2005342433.10 ppm
2019-07-02NOX 2005387712.72 ppm
2019-07-02NOX 2005387824.34 ppm
2019-07-18NOX 2005411472.27 ppm
2019-10-03NOX 2005513714.02 ppm
2020-01-02NOX 2005615030.125 ppm
2020-01-09NOX 2005623680.139 ppm
2020-01-15IOCR 2005631110.162 ppm
2020-03-24NOX 2005703693.12 ppm
2020-06-10NOX 2005788043.37 ppm
2020-06-242005804530.1000 ppm
2020-08-1220058638710.1 ppm
2020-08-12NOX 2005863883.85 ppm
2020-08-14CG540629.28 ppm
2020-09-09NOX 2005896642.02 ppm
2020-09-14NOX 2005901102.47 ppm
2020-09-14NOX 2005901170.630 ppm
2020-09-14NOX 2005901232.17 ppm
2020-09-14NOX 2005901251.87 ppm
2020-09-14NOX 2005901142.86 ppm
2020-10-07NOX 2005931693.82 ppm
2021-01-07NOX 2006030664.04 ppm
2021-02-17NOX 2006071030.150 ppm
2021-03-05IOCR 2006087090.145 ppm
2021-03-05NOX 2006087090.145 ppm
2021-04-12NOX 2006127313.46 ppm
2021-06-07NOX 2006198422.19 ppm
2021-06-07NOX 2006198432.99 ppm
2021-06-07NOX 2006214222.90 ppm
2021-07-07NOX 2006235993.97 ppm
2021-09-14300059920 3000599211.86 ppm
2021-09-14300059931 3000599330.598 ppm
2021-10-05N300075495 3000754962.26 ppm
2022-01-12CK150303.39 ppm
2022-01-12CK150310.470 ppm
2022-01-12CK150271.83 ppm
2022-01-24CK222940.610 ppm
2022-01-25CK231810.150 ppm
2022-01-25CK231762.99 ppm
2022-02-01CK274300.190 ppm
2022-02-01CK274340.170 ppm
2022-02-16CK693573.03 ppm
2022-02-16CK693582.94 ppm
2022-06-08CL522103.01 ppm
2022-06-14CL566402.39 ppm
2022-06-15CL580074.08 ppm
2022-07-11CL748953.81 ppm
2022-09-08CM256720.170 ppm
2022-09-20CM372951.99 ppm
2022-11-03CM766134.33 ppm
2023-01-10CN197350.0800 ppm
2023-01-10CN207423.10 ppm
2023-01-11CN209570.1000 ppm
2023-01-18CN250960.140 ppm
2023-02-01CN334430.140 ppm
2023-02-22CN479950.450 ppm
2023-02-22CN478692.82 ppm
2023-04-03CN747091.92 ppm
2023-04-11CN812193.11 ppm
2023-05-22CO116713.19 ppm
2023-07-05CO437974.04 ppm
2023-10-04CP178343.88 ppm
2023-10-31CP383311.40 ppm
2023-12-13CP672692.13 ppm