Nitrate and nitrite

Aquarion Water Company of Connecticut - Greenwich 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.

MORE ABOUT THIS CONTAMINANT

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	0.421 ppm	4	4	0.294 ppm - 0.549 ppm
2015	N/A	0	0	N/A
2016	0.171 ppm	4	4	0.0120 ppm - 0.396 ppm
2017	0.322 ppm	4	4	0.121 ppm - 0.527 ppm
2018	0.320 ppm	5	5	0.291 ppm - 0.346 ppm
2019	0.304 ppm	4	4	0.126 ppm - 0.499 ppm

ppm = parts per million

State and national drinking water standards and health guidelines

EWG Health Guideline 0.14 ppm

The 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
2014-04-01	201404201-IOCR	0.294 ppm
2014-04-01	201404209-NOX	0.545 ppm
2014-04-01	201404210-IOCR	0.549 ppm
2014-04-01	201404200-NOX	0.297 ppm
2016-06-07	201607107-NOX	0.0180 ppm
2016-06-07	201607117-NOX	0.396 ppm
2016-06-07	201607108-IOCR	0.0120 ppm
2016-06-20	201607794-IOCR	0.258 ppm
2017-04-03	201704555-IOCR	0.121 ppm
2017-04-03	201704568-IOCR	0.509 ppm
2017-04-03	201704567-NOX	0.527 ppm
2017-04-03	201704556-NOX	0.131 ppm
2018-04-02	201803873-NOX	0.312 ppm
2018-04-02	201803870-NOX	0.326 ppm
2018-04-02	201803870-IOCR	0.326 ppm
2018-10-01	201815017-NOX	0.291 ppm
2018-10-01	201815016-IOCR	0.346 ppm
2019-04-01	201904114-NOX	0.132 ppm
2019-04-01	201904109-NOX	0.499 ppm
2019-04-01	201904111-IOCR	0.126 ppm
2019-04-01	201904110-IOCR	0.458 ppm