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Private Wells and Nitrate

Naturally occurring nitrate can be found in groundwater and surface water at levels that do not generally cause health problems.

The most common way of ingesting nitrates is through drinking water. Once taken into the body, nitrates are converted to nitrites.

Nitrogen is essential for all living things, but high levels of nitrate in drinking water can be dangerous to health.

Sources of nitrates in drinking water can include runoff from fertilizer use; leaking from septic tanks, sewage; and erosion of natural deposits.

Nitrate toxicity could cause illness, with the most vulnerable population being infants. Infants below four months who drink water containing nitrate above 10 mg/L could become seriously ill with blue baby syndrome (methemoglobinemia). Symptoms of this nitrate toxicity include shortness of breath and bluish skin coloring.

Learn more about Nitrate and Health.
Levels of various naturally-occurring and man-made constituents in New Mexico groundwater including nitrate, might be elevated above the Environmental Protection Agency (EPA) Safe Drinking Water standards of 10 milligrams per liter (mg/L). Ongoing drought conditions and aquifer mining have raised further concern that increases in constituents may occur in the absence of significant ground water recharge events. To assure that the water is safe for human consumption, well owners should periodically test their wells.

The information available on this page, including the maps, demonstrates nitrate found in tested private wells in New Mexico based on the data available from various sources.

To know the nitrate concentration in your water from your own well, you need to test. It is important to know your water chemistry before choosing a treatment system.

Learn about testing.

Learn about treatment.

Wells Sampled 2004-2018


Nitrate levels in water samples from private wells vary between New Mexico counties and even within the same county. The groundwater system in New Mexico is very complex. This complexity can lead to large nitrate concentration variability even amongst neighboring wells. Therefore, to know the nitrate concentration in your water from your own well, you need to test.

The safe drinking water concentration for nitrate is 10 milligrams per liter (mg/L) and some of the water samples from wells in counties (with greater than 20 samples), appear to exceed this Environmental Protection Agency (EPA) Safe Drinking Water standard. Based on data available, counties without water samples that exceed the EPA drinking water standard include: De Baca, Sierra, and Union counties.

Drinking water containing nitrate more than EPA's standard could cause illness, with the most vulnerable population being infants. Infants below four months who drink water containing nitrate above 10 mg/L could become seriously ill with blue baby syndrome (methemoglobinemia). Symptoms of this nitrate toxicity include shortness of breath and bluish skin coloring.
Learn more about Nitrate and Health.

Nitrate Concentrations Over Time


The chart shows average private wells nitrate concentrations (mg/L) by county from 2004-2018. Five-year groupings (2004-2008, 2009-2013, 2014-2018). Average concentrations shown by county and year group with 20 or more samples available. Nitrate levels can fluctuate over time, it is recommended you test for nitrate in your well water yearly (spring-time is recommended).
Average Nitrate Concentration (mg/L) by County and Year (Five Year Grouping) 2004-2018

Nitrate Distribution (maps)


Nitrate Distribution in New Mexico Private Wells (Wells Sampled June 2004 - Apr 2018
Nitrate Distribution in New Mexico Private Wells (Wells Sampled June 2004 - Apr 2018
Nitrate Distribution in New Mexico Private Wells (Wells Sampled June 2004 - Apr 2018, Percentage of Samples Exceeding the EPA MCL of 10 mg/L for Nitrate
Nitrate Distribution in New Mexico Private Wells Inventory (Wells Sampled June 2004 - Apr 2018, Nitrate Test Results Summary
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Content updated: Fri, 19 Jul 2019 13:12:18 MDT