Nitrate

Seattle Public Utilities

Nitrate, a fertilizer chemical, frequently contaminates drinking water due to agricultural and urban runoff, and discharges from municipal wastewater treatment plants and septic tanks. Excessive nitrate in water can cause oxygen deprivation in infants and increase the risk of cancer. 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	0.0655 ppm	2	2	0.0170 ppm - 0.114 ppm
2015	0.0283 ppm	4	2	ND - 0.0990 ppm
2016	0.0545 ppm	2	2	0.0180 ppm - 0.0910 ppm
2017	ND	2	0	ND
2018	0.207 ppm	7	4	ND - 1.18 ppm
2019	0.0550 ppm	2	1	ND - 0.110 ppm

ppm = parts per million

State and national drinking water standards and health guidelines

EWG Health Guideline 0.14 ppm

The EWG Health Guideline of 0.14 ppm for nitrate was defined by EWG . This health guideline protects against cancer and harm to fetal growth and development.

EPA Maximum Contaminant
Level (MCL) 10 ppm

The legal limit for nitrate, established in 1962, was developed to protect infants from acute methemoglobinemia, a life-threatening disorder of oxygen transport in the body. This limit does not fully protect against the risk of cancer and harm to the developing fetus.

ppm = parts per million

All test results

Date	Lab ID	Result
2014-05-13	01097	0.114 ppm
2014-05-13	01096	0.0170 ppm
2015-06-23	01101	0.0990 ppm
2015-06-23	01100	0.0140 ppm
2015-07-28	01106	ND
2015-12-22	01109	ND
2016-05-24		0.0180 ppm
2016-05-24		0.0910 ppm
2017-06-06		ND
2017-06-06		ND
2018-02-07		ND
2018-02-07		ND
2018-06-12		ND
2018-06-12		0.0710 ppm
2018-10-03		1.18 ppm
2018-10-03		0.1000 ppm
2018-10-03		0.1000 ppm
2019-12-17		ND
2019-12-17		0.110 ppm