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EWG's Tap Water Database — 2021 UPDATE

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Nitrate and nitrite

Norman

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

 

186

Samples

0

Samples exceeding legal limit (MCL)

137

Samples exceeding
health guidelines

Testing results - average by year

 
YearAverage resultSamples takenDetectionsRange of results
2013N/A00N/A
20140.262 ppm3122ND - 0.658 ppm
20150.116 ppm319ND - 0.775 ppm
20160.439 ppm3121ND - 1.47 ppm
20170.556 ppm3834ND - 2.28 ppm
20180.354 ppm2724ND - 0.758 ppm
20190.399 ppm2827ND - 0.721 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
2014-07-301322166ND
2014-07-301322167ND
2014-07-301322168ND
2014-07-301322169ND
2014-07-301322170ND
2014-07-301322171ND
2014-07-3013221720.432 ppm
2014-07-301322173ND
2014-07-301322174ND
2014-10-2913460270.386 ppm
2014-10-2913460280.229 ppm
2014-10-2913460290.243 ppm
2014-10-2913460300.300 ppm
2014-10-291346031ND
2014-10-2913460330.387 ppm
2014-10-2913460350.342 ppm
2014-10-2913460360.327 ppm
2014-10-2913460370.468 ppm
2014-10-2913460380.410 ppm
2014-11-1813513640.658 ppm
2014-11-1813513660.238 ppm
2014-11-1913517680.394 ppm
2014-11-1913517730.459 ppm
2014-11-1913517770.350 ppm
2014-11-1913517780.291 ppm
2014-11-1913517820.419 ppm
2014-11-1913517850.212 ppm
2014-11-1913517860.531 ppm
2014-11-1913517870.272 ppm
2014-12-1513577490.340 ppm
2014-12-1713590890.430 ppm
2015-03-0313760460.251 ppm
2015-03-0313760470.269 ppm
2015-03-0313760480.260 ppm
2015-03-0313760490.775 ppm
2015-06-151402904ND
2015-07-1414105620.245 ppm
2015-07-1414105650.212 ppm
2015-07-141410566ND
2015-07-271413771ND
2015-08-1114181150.623 ppm
2015-09-081425584ND
2015-09-171428511ND
2015-09-171428512ND
2015-09-171428513ND
2015-09-171428514ND
2015-09-171428515ND
2015-09-241430187ND
2015-10-131435400ND
2015-10-131435402ND
2015-10-131435404ND
2015-10-191436494ND
2015-10-2014370780.377 ppm
2015-10-221437898ND
2015-12-031449236ND
2015-12-031449237ND
2015-12-151451832ND
2015-12-151451834ND
2015-12-1514518350.598 ppm
2015-12-151451836ND
2015-12-151451837ND
2015-12-151451838ND
2016-01-121458360ND
2016-01-121458363ND
2016-01-1214583641.04 ppm
2016-01-1914600051.44 ppm
2016-01-1914600081.47 ppm
2016-02-021464026ND
2016-02-041465011ND
2016-02-091466179ND
2016-03-0114712320.610 ppm
2016-03-0114712340.567 ppm
2016-03-0114712350.207 ppm
2016-04-1214822710.949 ppm
2016-05-1014902330.342 ppm
2016-05-1014902340.362 ppm
2016-05-101490235ND
2016-05-101490237ND
2016-05-101490238ND
2016-05-101490239ND
2016-06-0214964430.585 ppm
2016-06-0214964440.383 ppm
2016-06-0214964450.835 ppm
2016-06-0214964470.530 ppm
2016-06-0214964480.344 ppm
2016-06-0214964490.489 ppm
2016-06-0214964500.340 ppm
2016-08-1115155391.05 ppm
2016-08-1115694961.05 ppm
2016-09-2215270090.369 ppm
2016-09-221527014ND
2016-09-2215270530.420 ppm
2016-09-2315270550.226 ppm
2017-01-0415529190.949 ppm
2017-01-0415529200.302 ppm
2017-01-0515533570.669 ppm
2017-01-0515533712.02 ppm
2017-01-0515533720.379 ppm
2017-01-1115547290.632 ppm
2017-02-0915625690.519 ppm
2017-02-0915625710.897 ppm
2017-02-0915625720.538 ppm
2017-02-0915625730.276 ppm
2017-02-0915625740.459 ppm
2017-02-0915625850.488 ppm
2017-02-2115658710.286 ppm
2017-02-2315667220.530 ppm
2017-03-0915706150.639 ppm
2017-03-0915706160.738 ppm
2017-03-0915706170.433 ppm
2017-03-0915706180.752 ppm
2017-03-3015757090.506 ppm
2017-03-301575711ND
2017-03-3015757120.293 ppm
2017-03-3015757131.05 ppm
2017-03-3015757140.398 ppm
2017-03-3015757150.579 ppm
2017-03-301575716ND
2017-04-041576612ND
2017-04-041576613ND
2017-06-0815949660.620 ppm
2017-06-0815949672.01 ppm
2017-06-0815949682.28 ppm
2017-06-0815949690.239 ppm
2017-06-0815949700.222 ppm
2017-06-0815949710.189 ppm
2017-06-0815949720.267 ppm
2017-08-0216100640.232 ppm
2017-08-0216229760.232 ppm
2017-10-0916285200.332 ppm
2017-10-0916285330.184 ppm
2018-02-08AB08090-010.312 ppm
2018-02-08AB08090-020.223 ppm
2018-02-08AB08090-030.622 ppm
2018-02-08AB08090-040.650 ppm
2018-02-08AB08090-050.445 ppm
2018-02-08AB08090-060.297 ppm
2018-02-08AB08091-010.361 ppm
2018-02-08AB08091-020.210 ppm
2018-02-15AB15084-010.417 ppm
2018-02-15AB15084-030.441 ppm
2018-02-15AB15084-040.525 ppm
2018-02-15AB15084-050.240 ppm
2018-02-15AB15084-060.211 ppm
2018-02-15AB15084-070.601 ppm
2018-02-22AB22064-010.551 ppm
2018-02-22AB22064-020.177 ppm
2018-02-22AB22064-03ND
2018-02-22AB22064-040.207 ppm
2018-02-22AB22064-050.185 ppm
2018-02-22AB22064-060.171 ppm
2018-02-22AB22064-070.219 ppm
2018-02-22AB22064-080.373 ppm
2018-02-281665727ND
2018-02-281665728ND
2018-03-08AC08106-030.736 ppm
2018-03-08AC08106-040.635 ppm
2018-05-03AE03121-020.758 ppm
2019-02-20BB21080-010.374 ppm
2019-02-20BB21080-030.675 ppm
2019-02-20BB21080-040.487 ppm
2019-02-20BB21080-050.615 ppm
2019-02-20BB21080-060.613 ppm
2019-02-20BB21080-070.679 ppm
2019-02-25BB28051-050.536 ppm
2019-02-25BB28051-080.223 ppm
2019-02-26BB28051-020.448 ppm
2019-02-26BB28051-090.339 ppm
2019-02-26BB28051-100.533 ppm
2019-02-26BB28051-110.287 ppm
2019-02-26BB28051-120.253 ppm
2019-03-05BC12026-010.190 ppm
2019-03-05BC12026-020.346 ppm
2019-03-05BC12026-030.721 ppm
2019-03-05BC12026-040.381 ppm
2019-03-05BC12026-050.571 ppm
2019-03-06BC12026-09ND
2019-03-06BC12026-100.467 ppm
2019-03-06BC12026-110.250 ppm
2019-03-11BC12026-060.226 ppm
2019-04-04BD04068-020.274 ppm
2019-04-10BD11084-020.200 ppm
2019-04-10BD11084-030.200 ppm
2019-04-22BD25045-010.243 ppm
2019-05-29BE30060-030.412 ppm
2019-07-22BG25082-020.617 ppm