EWG's Tap Water Database — 2019 UPDATE



City of Post Falls

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.





Samples exceeding legal limit (MCL)


Samples exceeding
health guidelines

Testing results - average by year

YearAverage resultSamples takenDetectionsRange of results
20120.909 ppm1514ND - 1.50 ppm
20130.943 ppm109ND - 1.39 ppm
20140.853 ppm13130.0580 ppm - 1.34 ppm
20150.812 ppm15150.310 ppm - 1.09 ppm
20160.796 ppm1413ND - 1.11 ppm
20170.771 ppm11110.330 ppm - 1.45 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
2012-06-11I0611121041.000 ppm
2012-06-11I0611121030.280 ppm
2012-06-11I0611121051.40 ppm
2012-06-11I0611121290.619 ppm
2012-09-10N1339471.26 ppm
2012-09-10N1339490.940 ppm
2012-09-10N1339501.38 ppm
2012-09-10N1339510.950 ppm
2012-09-10N1339521.30 ppm
2012-09-10N1339460.950 ppm
2012-09-24I0924121041.15 ppm
2012-09-24I0924121030.316 ppm
2012-09-24I0924121051.50 ppm
2012-09-24I0924121290.591 ppm
2013-06-19I1411551.39 ppm
2013-06-19I1411541.19 ppm
2013-06-19I1411531.18 ppm
2013-06-19I1411520.810 ppm
2013-06-20I1411941.29 ppm
2013-09-23I0923131041.28 ppm
2013-09-23I0923131030.267 ppm
2013-09-23I0923131051.32 ppm
2013-09-23I0923131290.703 ppm
2014-01-27I0127141290.514 ppm
2014-01-27I0127141051.14 ppm
2014-01-27I12801471.12 ppm
2014-03-21N1490780.0580 ppm
2014-06-02I0602141041.32 ppm
2014-06-02I0602141030.288 ppm
2014-06-02I0602141051.34 ppm
2014-06-02I0602141290.804 ppm
2014-09-04N1542830.830 ppm
2014-09-04N1542820.770 ppm
2014-09-04N1542810.980 ppm
2014-09-04N1542801.12 ppm
2014-09-04N1542790.800 ppm
2015-03-18I0318151430.862 ppm
2015-03-18I0318151290.349 ppm
2015-03-18I0318151030.670 ppm
2015-07-14I0714151430.995 ppm
2015-07-14I0714151290.531 ppm
2015-07-14I0714151041.06 ppm
2015-07-14I0714151030.310 ppm
2015-09-14N1645900.890 ppm
2015-09-14N1645890.730 ppm
2015-09-14N1645881.09 ppm
2015-09-14N1645870.960 ppm
2015-11-17I1117151430.996 ppm
2015-11-17I1117151290.777 ppm
2015-11-17I1117151041.01 ppm
2015-11-17I1117150.945 ppm
2016-03-22N0322161430.918 ppm
2016-03-22N0322161031.000 ppm
2016-03-22N0322161041.11 ppm
2016-07-19N0719161430.835 ppm
2016-07-190719161290.452 ppm
2016-07-19N0719161040.886 ppm
2016-07-19N0719161030.407 ppm
2016-12-13N1782991.02 ppm
2016-12-13N1782980.970 ppm
2016-12-13I1782970.820 ppm
2016-12-14I1783640.980 ppm
2016-12-14I1783631.03 ppm
2016-12-14I1783620.710 ppm
2017-03-14I1703140600041430.700 ppm
2017-03-14I1703140600031040.983 ppm
2017-03-14I1703140600021290.330 ppm
2017-03-14I1703140600011030.474 ppm
2017-07-18I1704180470011030.712 ppm
2017-07-18I1704180470021290.584 ppm
2017-07-18I1704180470031041.45 ppm
2017-07-18I1704180470041430.885 ppm
2017-12-15N1893750.530 ppm
2017-12-15N1893760.730 ppm
2017-12-15N1893771.10 ppm