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EWG's Tap Water Database — 2021 UPDATE

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Nitrate and nitrite

Regional Water Authority

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

 

132

Samples

0

Samples exceeding legal limit (MCL)

118

Samples exceeding
health guidelines

Testing results - average by year

 
YearAverage resultSamples takenDetectionsRange of results
20141.30 ppm25250.0470 ppm - 3.40 ppm
2015N/A00N/A
20161.16 ppm27270.0250 ppm - 3.26 ppm
20171.18 ppm27270.0430 ppm - 4.07 ppm
20181.26 ppm27270.0900 ppm - 3.79 ppm
20191.48 ppm26260.0200 ppm - 3.80 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
2014-02-24IOCR 2003914763.21 ppm
2014-02-24IOCR 2003914780.849 ppm
2014-02-24IOCR 2003914801.16 ppm
2014-02-24IOCR 2003914812.73 ppm
2014-02-24IOCR 2003914822.35 ppm
2014-02-25IOCR 2003916020.0510 ppm
2014-02-25IOCR 2003916030.360 ppm
2014-02-25IOCR 2003916210.200 ppm
2014-02-25IOCR 2003916243.01 ppm
2014-02-25IOCR 2003916251.98 ppm
2014-02-25NOX 2003915990.0470 ppm
2014-02-25NOX 2003916000.360 ppm
2014-02-25NOX 2003916163.40 ppm
2014-02-25NOX 2003916171.03 ppm
2014-02-25NOX 2003916183.09 ppm
2014-02-25NOX 2003916192.77 ppm
2014-02-25NOX 2003916200.197 ppm
2014-02-25NOX 2003916530.695 ppm
2014-02-26IOCR 2003917271.26 ppm
2014-03-18IOCR 2003928060.745 ppm
2014-05-13IOCR 2003958560.688 ppm
2014-05-13IOCR 2003958620.720 ppm
2014-05-13IOCR 2003958630.404 ppm
2014-05-13NOX 2003958550.453 ppm
2014-05-13NOX 2003958600.714 ppm
2016-02-08IOCR 2004333352.43 ppm
2016-02-08IOCR 2004333401.92 ppm
2016-02-08IOCR 2004333412.84 ppm
2016-02-08IOCR 2004333360.812 ppm
2016-02-08IOCR 2004333380.761 ppm
2016-02-09IOCR 2004334240.382 ppm
2016-02-09NOX 2004334113.24 ppm
2016-02-09NOX 2004334142.31 ppm
2016-02-09NOX 2004334120.854 ppm
2016-02-09NOX 2004334132.64 ppm
2016-02-09NOX 2004334790.836 ppm
2016-02-09NOX 2004333970.0270 ppm
2016-02-09NOX 2004333980.198 ppm
2016-02-09NOX 2004334150.101 ppm
2016-02-09NOX 2004334250.390 ppm
2016-02-09IOCR 2004334203.26 ppm
2016-02-09IOCR 2004334190.886 ppm
2016-02-09IOCR 2004334182.63 ppm
2016-02-09IOCR 2004334800.803 ppm
2016-02-09IOCR 2004333990.0250 ppm
2016-02-09IOCR 2004334000.197 ppm
2016-02-09IOCR 2004334160.109 ppm
2016-02-10IOCR 2004335491.38 ppm
2016-05-12NOX 2004395130.490 ppm
2016-05-12NOX 2004395150.448 ppm
2016-05-12IOCR 2004395140.476 ppm
2016-11-22IOCR 2004552691.000 ppm
2017-03-20IOCR 2004626402.70 ppm
2017-03-20IOCR 2004626462.39 ppm
2017-03-20IOCR 2004626410.793 ppm
2017-03-20IOCR 2004626420.703 ppm
2017-03-20IOCR 2004626452.80 ppm
2017-03-21IOCR 2004627750.477 ppm
2017-03-21NOX 2004627392.81 ppm
2017-03-21NOX 2004627422.69 ppm
2017-03-21NOX 2004627400.741 ppm
2017-03-21NOX 2004627412.79 ppm
2017-03-21NOX 2004627930.667 ppm
2017-03-21NOX 2004627560.0520 ppm
2017-03-21NOX 2004627570.203 ppm
2017-03-21NOX 2004627430.144 ppm
2017-03-21NOX 2004627770.482 ppm
2017-03-21IOCR 2004628331.62 ppm
2017-03-21IOCR 2004627644.07 ppm
2017-03-21IOCR 2004627940.595 ppm
2017-03-21IOCR 2004627950.800 ppm
2017-03-21IOCR 2004627580.0430 ppm
2017-03-21IOCR 2004627590.185 ppm
2017-03-21IOCR 2004627440.164 ppm
2017-06-19IOCR 2004696861.06 ppm
2017-06-20NOX 2004698120.840 ppm
2017-06-20NOX 2004698270.632 ppm
2017-06-20IOCR 2004698280.653 ppm
2017-06-20IOCR 2004698130.760 ppm
2018-03-12IOCR 2004897602.43 ppm
2018-03-12IOCR 2004897580.757 ppm
2018-03-12IOCR 2004897593.02 ppm
2018-03-14IOCR 2004899110.380 ppm
2018-03-14NOX 2004898672.47 ppm
2018-03-14NOX 2004898702.70 ppm
2018-03-14NOX 2004898681.04 ppm
2018-03-14NOX 2004898840.114 ppm
2018-03-14NOX 2004898850.270 ppm
2018-03-14NOX 2004898710.388 ppm
2018-03-14NOX 2004899130.414 ppm
2018-03-14NOX 2004899140.947 ppm
2018-03-14IOCR 2004898981.72 ppm
2018-03-14IOCR 2004899003.24 ppm
2018-03-14IOCR 2004898961.15 ppm
2018-03-14IOCR 2004899120.930 ppm
2018-03-14IOCR 2004898860.0900 ppm
2018-03-14IOCR 2004898870.240 ppm
2018-03-14IOCR 2004898720.373 ppm
2018-03-14IOCR 2004898970.972 ppm
2018-03-15NOX 2004900612.97 ppm
2018-03-15IOCR 2004900623.79 ppm
2018-03-15IOCR 2004900630.577 ppm
2018-03-23IOCR 2004905120.665 ppm
2018-11-29NOX 2005140970.872 ppm
2018-11-29NOX 2005141120.732 ppm
2018-11-29IOCR 2005141140.849 ppm
2019-03-18NOX 2005248951.17 ppm
2019-03-18IOCR 2005248963.37 ppm
2019-03-18IOCR 2005249033.80 ppm
2019-03-18IOCR 2005249011.31 ppm
2019-03-18IOCR 2005249023.07 ppm
2019-03-18IOCR 2005249050.981 ppm
2019-03-18IOCR 2005249001.48 ppm
2019-03-19IOCR 2005250950.526 ppm
2019-03-19NOX 2005250572.58 ppm
2019-03-19NOX 2005250603.72 ppm
2019-03-19NOX 2005250581.44 ppm
2019-03-19NOX 2005250593.10 ppm
2019-03-19NOX 2005250770.0200 ppm
2019-03-19NOX 2005250780.0510 ppm
2019-03-19NOX 2005250610.316 ppm
2019-03-19NOX 2005250970.491 ppm
2019-03-19NOX 2005250980.791 ppm
2019-03-19IOCR 2005250651.76 ppm
2019-03-19IOCR 2005250663.73 ppm
2019-03-19IOCR 2005250641.52 ppm
2019-03-19IOCR 2005250960.813 ppm
2019-03-19IOCR 2005250790.0480 ppm
2019-03-19IOCR 2005250800.0640 ppm
2019-03-19IOCR 2005250620.290 ppm
2019-05-08NOX 2005312970.986 ppm
2019-05-08IOCR 2005313031.01 ppm