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EWG's Tap Water Database — 2021 UPDATE

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Nitrate

San Antonio Water System

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.

MORE ABOUT THIS CONTAMINANT

 

261

Samples

0

Samples exceeding legal limit (MCL)

242

Samples exceeding
health guidelines

Testing results - average by year

 
YearAverage resultSamples takenDetectionsRange of results
20141.54 ppm38380.0300 ppm - 2.54 ppm
20151.73 ppm36360.0500 ppm - 2.51 ppm
20161.87 ppm4645ND - 2.84 ppm
20171.55 ppm5346ND - 2.79 ppm
20181.82 ppm44440.1000 ppm - 3.14 ppm
20191.78 ppm44440.0600 ppm - 2.68 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
2014-01-13AC385082.10 ppm
2014-01-13AC385051.53 ppm
2014-01-13AC385072.02 ppm
2014-01-13AC385061.90 ppm
2014-01-14AC387070.0400 ppm
2014-01-14AC387090.0400 ppm
2014-01-14AC387102.19 ppm
2014-01-14AC387080.700 ppm
2014-03-31AC485991.89 ppm
2014-03-31AC486212.16 ppm
2014-03-31AC486221.43 ppm
2014-03-31AC486192.01 ppm
2014-03-31AC486201.000 ppm
2014-05-13AC539172.26 ppm
2014-05-13AC539160.1000 ppm
2014-05-13AC539312.40 ppm
2014-06-30AC583742.08 ppm
2014-06-30AC583751.97 ppm
2014-06-30AC583731.75 ppm
2014-07-29AC612790.780 ppm
2014-07-29AC612810.960 ppm
2014-07-29AC612762.32 ppm
2014-07-29AC612800.0300 ppm
2014-07-30AC614821.89 ppm
2014-07-31AC616982.54 ppm
2014-09-02AC654012.11 ppm
2014-09-03AC655841.62 ppm
2014-09-29AC683312.21 ppm
2014-09-29AC683322.17 ppm
2014-09-29AC683330.160 ppm
2014-09-29AC683460.180 ppm
2014-09-30AC684931.75 ppm
2014-09-30AC684961.95 ppm
2014-09-30AC684952.04 ppm
2014-09-30AC684941.89 ppm
2014-11-25AC729351.49 ppm
2014-11-25AC729372.22 ppm
2014-12-02AC732820.680 ppm
2015-03-05AC827602.12 ppm
2015-04-02AC870402.12 ppm
2015-04-02AC870391.58 ppm
2015-04-02AC870421.28 ppm
2015-04-02AC870440.0500 ppm
2015-04-02AC870432.03 ppm
2015-04-02AC870411.90 ppm
2015-07-07AC984761.66 ppm
2015-07-07AC984730.940 ppm
2015-07-30AD016912.24 ppm
2015-07-30AD016902.09 ppm
2015-07-30AD016921.05 ppm
2015-07-30AD016932.44 ppm
2015-07-30AD016891.94 ppm
2015-09-28AD086382.09 ppm
2015-09-28AD086372.06 ppm
2015-09-28AD086391.97 ppm
2015-09-28AD086542.10 ppm
2015-09-29AD088891.83 ppm
2015-09-29AD088861.80 ppm
2015-09-29AD088902.02 ppm
2015-09-29AD088871.62 ppm
2015-10-27AD117631.41 ppm
2015-10-27AD117640.0900 ppm
2015-10-28AD119022.12 ppm
2015-10-28AD119012.27 ppm
2015-10-28AD119030.540 ppm
2015-10-28AD118991.78 ppm
2015-10-28AD119000.980 ppm
2015-10-28AD118982.09 ppm
2015-10-28AD119290.740 ppm
2015-11-23AD143442.38 ppm
2015-11-23AD143412.19 ppm
2015-11-23AD143422.51 ppm
2015-11-23AD143432.24 ppm
2015-11-23AD143521.94 ppm
2016-01-13AD177610.790 ppm
2016-01-14AD181021.83 ppm
2016-04-05AD317542.17 ppm
2016-04-05AD317581.59 ppm
2016-04-05AD317571.90 ppm
2016-04-05AD317561.97 ppm
2016-04-05AD317551.85 ppm
2016-04-06AD319692.14 ppm
2016-04-06AD319541.99 ppm
2016-04-06AD319532.15 ppm
2016-04-06AD319522.00 ppm
2016-04-06AD319512.13 ppm
2016-04-07AD322161.79 ppm
2016-04-07AD322062.01 ppm
2016-04-07AD322011.69 ppm
2016-04-07AD322022.18 ppm
2016-04-07AD322031.64 ppm
2016-04-07AD322042.03 ppm
2016-06-28AD420452.13 ppm
2016-10-06AD525961.87 ppm
2016-10-06AD525972.32 ppm
2016-10-31AD553152.16 ppm
2016-11-02AD560330.460 ppm
2016-11-02AD560312.59 ppm
2016-11-02AD560322.84 ppm
2016-11-02AD560242.34 ppm
2016-11-02AD559972.68 ppm
2016-11-03AD563681.43 ppm
2016-11-03AD563662.19 ppm
2016-11-03AD563652.41 ppm
2016-11-03AD563670.950 ppm
2016-11-04AD566962.05 ppm
2016-11-04AD566942.12 ppm
2016-11-04AD566982.07 ppm
2016-11-28AD591452.69 ppm
2016-11-28AD591331.74 ppm
2016-11-28AD591321.69 ppm
2016-11-28AD591312.04 ppm
2016-11-28AD591341.74 ppm
2016-11-29AD592912.16 ppm
2016-11-29AD592901.99 ppm
2016-11-29AD592612.07 ppm
2016-11-29AD592602.36 ppm
2016-11-29AD592630.150 ppm
2016-11-29AD592620.790 ppm
2016-12-01AD59725ND
2017-01-30AD67403ND
2017-01-30AD67402ND
2017-01-30AD67401ND
2017-01-30AD67349ND
2017-01-30AD67350ND
2017-01-30AD67351ND
2017-02-01AD679821.73 ppm
2017-02-01AD679701.40 ppm
2017-02-02AD68267ND
2017-03-06AD733412.06 ppm
2017-03-06AD733460.410 ppm
2017-03-06AD733142.21 ppm
2017-03-29AD773282.10 ppm
2017-03-29AD773291.53 ppm
2017-03-29AD773271.88 ppm
2017-03-29AD773301.87 ppm
2017-03-29AD773261.86 ppm
2017-03-30AD776382.18 ppm
2017-03-30AD776392.49 ppm
2017-03-30AD776342.19 ppm
2017-07-06AD884062.10 ppm
2017-07-06AD883882.18 ppm
2017-09-11AD953410.940 ppm
2017-09-11AD953472.06 ppm
2017-09-11AD953481.40 ppm
2017-10-17AE009582.14 ppm
2017-10-18AE012372.06 ppm
2017-10-18AE012381.64 ppm
2017-10-18AE012392.02 ppm
2017-12-04AE064922.49 ppm
2017-12-04AE064750.410 ppm
2017-12-04AE064742.35 ppm
2017-12-05AE066931.95 ppm
2017-12-05AE066941.84 ppm
2017-12-05AE066581.96 ppm
2017-12-06AE069042.05 ppm
2017-12-06AE068682.79 ppm
2017-12-06AE068712.37 ppm
2017-12-06AE068691.19 ppm
2017-12-06AE068701.93 ppm
2017-12-07AE071291.73 ppm
2017-12-07AE071261.45 ppm
2017-12-07AE071282.09 ppm
2017-12-07AE071301.58 ppm
2017-12-07AE071171.49 ppm
2017-12-07AE071161.74 ppm
2017-12-08AE073560.610 ppm
2017-12-08AE073570.0700 ppm
2017-12-08AE073721.76 ppm
2017-12-13AE076012.01 ppm
2017-12-13AE075991.67 ppm
2017-12-13AE076002.25 ppm
2017-12-20AE078661.81 ppm
2018-03-01AE162100.510 ppm
2018-03-01AE162092.39 ppm
2018-03-01AE162321.06 ppm
2018-03-15AE184960.130 ppm
2018-03-26AE198141.67 ppm
2018-03-26AE198151.99 ppm
2018-05-22AE273560.760 ppm
2018-06-06AE287422.21 ppm
2018-06-06AE287412.04 ppm
2018-06-06AE287433.14 ppm
2018-07-23AE340120.1000 ppm
2018-09-26AE416572.08 ppm
2018-09-26AE416601.55 ppm
2018-09-26AE416551.98 ppm
2018-09-26AE416562.08 ppm
2018-09-26AE416581.75 ppm
2018-09-26AE416591.70 ppm
2018-09-27AE418681.86 ppm
2018-09-27AE418721.89 ppm
2018-09-27AE418711.88 ppm
2018-09-27AE418701.78 ppm
2018-09-27AE418731.43 ppm
2018-09-27AE418742.22 ppm
2018-09-27AE418691.61 ppm
2018-11-19AE463521.94 ppm
2018-11-19AE463452.19 ppm
2018-11-19AE463462.12 ppm
2018-11-19AE463432.20 ppm
2018-11-19AE463442.09 ppm
2018-11-20AE465472.12 ppm
2018-12-07AE483201.78 ppm
2018-12-07AE483181.73 ppm
2018-12-07AE483142.33 ppm
2018-12-07AE483252.08 ppm
2018-12-07AE483172.22 ppm
2018-12-07AE483212.46 ppm
2018-12-07AE483232.44 ppm
2018-12-07AE483152.40 ppm
2018-12-13AE487771.99 ppm
2018-12-13AE487732.13 ppm
2018-12-13AE487742.12 ppm
2018-12-13AE487751.26 ppm
2018-12-13AE487760.970 ppm
2018-12-13AE487721.79 ppm
2019-01-29AE518472.19 ppm
2019-01-29AE518352.07 ppm
2019-01-30AE521152.60 ppm
2019-01-30AE520882.68 ppm
2019-01-31AE523321.94 ppm
2019-01-31AE523311.70 ppm
2019-03-07AE575141.82 ppm
2019-03-07AE574992.12 ppm
2019-03-07AE574831.28 ppm
2019-03-07AE574842.23 ppm
2019-03-28AE603932.59 ppm
2019-03-28AE603942.11 ppm
2019-03-28AE603770.890 ppm
2019-04-23AE632781.77 ppm
2019-04-23AE632771.76 ppm
2019-04-25AE636550.900 ppm
2019-04-25AE636270.670 ppm
2019-05-21AE672872.24 ppm
2019-05-21AE672631.83 ppm
2019-05-21AE672601.77 ppm
2019-05-21AE672612.08 ppm
2019-05-21AE672641.81 ppm
2019-05-21AE672622.49 ppm
2019-08-13AE782042.02 ppm
2019-11-13AE890290.0600 ppm
2019-11-13AE890302.11 ppm
2019-11-14AE891832.14 ppm
2019-11-14AE891791.57 ppm
2019-11-14AE891821.93 ppm
2019-11-14AE891801.93 ppm
2019-11-14AE891812.13 ppm
2019-11-25AE903231.70 ppm
2019-11-25AE903242.03 ppm
2019-11-25AE902791.98 ppm
2019-11-25AE902772.39 ppm
2019-11-25AE902800.910 ppm
2019-11-25AE902780.120 ppm
2019-11-26AE905271.56 ppm
2019-11-26AE905011.69 ppm
2019-12-10AE917652.09 ppm
2019-12-10AE917642.13 ppm
2019-12-10AE917632.36 ppm
2019-12-11AE920581.27 ppm
2019-12-11AE920120.580 ppm