Nitrate and nitrite

Tri-County Water Distbr 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.

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	0.0300 ppm	4	1	ND - 0.120 ppm
2015	0.0500 ppm	4	1	ND - 0.200 ppm
2016	ND	5	0	ND
2017	0.0300 ppm	4	1	ND - 0.120 ppm
2018	0.0660 ppm	5	2	ND - 0.210 ppm
2019	0.0300 ppm	4	1	ND - 0.120 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
2014-02-25	140590016	0.120 ppm
2014-04-16	141070033	ND
2014-07-16	141980026	ND
2014-11-11	Y143160008	ND
2015-01-14	Y150150006	0.200 ppm
2015-04-15	Y151060030	ND
2015-08-17	Y152320029	ND
2015-10-20	Y152950005	ND
2016-02-08	Y160420037	ND
2016-02-29	Y160630013	ND
2016-05-23	Y161470035	ND
2016-08-03	Y162210071	ND
2016-11-01	Y163090003	ND
2017-01-31	Y170340011	ND
2017-06-27	Y171800067	ND
2017-08-08	Y172220041	ND
2017-11-07	Y173130007	0.120 ppm
2018-01-29	Y180330001	0.210 ppm
2018-05-21	Y181440009	ND
2018-07-31	Y182140013	ND
2018-09-17	Y182630014	ND
2018-10-22	Y182980006	0.120 ppm
2019-01-29	Y190310038	0.120 ppm
2019-05-13	Y191360016	ND
2019-08-27	Y192410027	ND
2019-10-14	Y192900006	ND