EWG's Tap Water Database — 2019 UPDATE



Harris County MUD 165

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
20120.165 ppm220.120 ppm - 0.210 ppm
20130.0925 ppm440.01000 ppm - 0.220 ppm
20140.123 ppm330.01000 ppm - 0.230 ppm
20150.120 ppm330.01000 ppm - 0.220 ppm
20160.123 ppm330.0200 ppm - 0.220 ppm
20170.113 ppm330.0200 ppm - 0.210 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
2012-01-11AB775190.120 ppm
2012-01-11AB775220.210 ppm
2013-06-13AC219780.0200 ppm
2013-06-13AC219620.220 ppm
2013-06-13AC219790.120 ppm
2013-09-11AC297760.01000 ppm
2014-03-20AC477560.01000 ppm
2014-03-20AC477620.230 ppm
2014-07-16AC597830.130 ppm
2015-05-27AC933520.01000 ppm
2015-05-27AC933310.220 ppm
2015-05-27AC933390.130 ppm
2016-03-21AD294610.220 ppm
2016-03-21AD295020.0200 ppm
2016-03-21AD295010.130 ppm
2017-05-04AD825950.0200 ppm
2017-05-04AD825920.110 ppm
2017-05-04AD826150.210 ppm