EWG's Tap Water Database — 2019 UPDATE


Nitrate and nitrite

Northwestern W and Sd-wtln 200

NOTE: Northwestern W and Sd-wtln 200 purchases water from Oregon City which is required to test for nitrate and nitrite. Sample information shown below was taken by Oregon City.

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.





Samples exceeding legal limit (MCL)


Samples exceeding
health guidelines

Testing results - average by year

YearAverage resultSamples takenDetectionsRange of results
20121.19 ppm1210ND - 2.85 ppm
20131.39 ppm1211ND - 4.95 ppm
20141.63 ppm129ND - 4.79 ppm
20151.25 ppm1211ND - 3.31 ppm
20161.52 ppm129ND - 5.02 ppm
20171.64 ppm1210ND - 4.01 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

NOTE: Northwestern W and Sd-wtln 200 purchases water from Oregon City which is required to test for nitrate and nitrite. Sample information shown below was taken by Oregon City.

Date Lab ID Result
2012-01-11AG128972.65 ppm
2012-02-07AG144982.85 ppm
2012-03-06AG161812.72 ppm
2012-04-12AG188412.62 ppm
2012-05-09AG206400.640 ppm
2012-06-14AG233090.550 ppm
2012-07-03AG245260.210 ppm
2012-08-07AG269120.310 ppm
2012-11-15AG341230.290 ppm
2012-12-04AG351851.49 ppm
2013-01-04AG371960.570 ppm
2013-02-05AG390112.24 ppm
2013-03-22AG420384.95 ppm
2013-04-04AG427920.930 ppm
2013-05-13AG455802.37 ppm
2013-06-14AG479142.02 ppm
2013-07-09AG496930.970 ppm
2013-08-20AG530901.25 ppm
2013-09-04AG540690.300 ppm
2013-11-14AG591380.470 ppm
2013-12-03AG602770.630 ppm
2014-01-09AG623754.24 ppm
2014-02-06AG641074.79 ppm
2014-03-19AG667092.56 ppm
2014-04-03AG675582.75 ppm
2014-05-19AG708382.08 ppm
2014-06-04AG720341.17 ppm
2014-07-09AG749730.730 ppm
2014-11-17AG851300.500 ppm
2014-12-04AG866190.760 ppm
2015-01-05AG883970.310 ppm
2015-02-09AG904762.06 ppm
2015-03-03AG916021.88 ppm
2015-04-08AG939922.15 ppm
2015-05-11AG961712.08 ppm
2015-06-10AG986141.39 ppm
2015-07-09AH007773.31 ppm
2015-08-18AH038820.520 ppm
2015-10-08AH075270.380 ppm
2015-11-17AH102330.640 ppm
2015-12-03AH112610.310 ppm
2016-01-14AH136473.68 ppm
2016-02-09AH150991.07 ppm
2016-03-22AH177915.02 ppm
2016-04-13AH192851.50 ppm
2016-05-20AH220872.25 ppm
2016-06-09AH235561.56 ppm
2016-07-12AH257541.64 ppm
2016-11-08AH355340.360 ppm
2016-12-06AH374461.20 ppm
2017-01-12AH404180.970 ppm
2017-02-09AH427052.22 ppm
2017-03-08AH446952.14 ppm
2017-04-11AH468562.31 ppm
2017-05-23AH503302.91 ppm
2017-06-06AH512704.01 ppm
2017-07-11AH542192.91 ppm
2017-08-10AH571020.800 ppm
2017-11-15AH644301.13 ppm
2017-12-06AH657810.300 ppm