Nitrate and nitrite

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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	2.96 ppm	4	3	ND - 6.25 ppm
2015	ND	5	0	ND
2016	0.616 ppm	5	1	ND - 3.08 ppm
2017	3.46 ppm	5	2	ND - 11.9 ppm
2018	3.98 ppm	8	6	ND - 12.5 ppm
2019	2.65 ppm	7	4	ND - 5.73 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
2014-03-27	281048	2.82 ppm
2014-05-28	293807	2.77 ppm
2014-07-29	308572	6.25 ppm
2014-12-29	329267	ND
2015-01-13	345294	ND
2015-01-13	345295	ND
2015-08-31	373926	ND
2015-12-16	391778	ND
2015-12-16	391779	ND
2016-01-20		ND
2016-08-31		3.08 ppm
2016-12-28		ND
2016-12-28		ND
2016-12-28		ND
2017-09-27		11.9 ppm
2017-11-20		ND
2017-11-20		ND
2017-11-20		ND
2017-11-30		5.41 ppm
2018-01-30	530985	7.22 ppm
2018-06-27	544572	2.89 ppm
2018-08-29	562394	12.5 ppm
2018-09-25	573647	2.87 ppm
2018-12-20	578524	6.29 ppm
2018-12-26	578521	0.0521 ppm
2018-12-26	578522	ND
2018-12-26	578523	ND
2019-02-27	591034	5.42 ppm
2019-06-26	603929	2.38 ppm
2019-08-27	618090	5.73 ppm
2019-10-15	640436	5.01 ppm
2019-11-25	638955	ND
2019-11-25	638956	ND
2019-11-25	638954	ND