Nitrate And Nitrite Nitrogen In Drinking Water

Water Wisdom Tips and Newsletter Issue # 7

In this issue of Water Wisdom, we'll discuss two important sources of drinking water contamination - nitrate and nitrite nitrogen. Because these are both forms of nitrogen, we'll take a look at how each one may infiltrate our drinking water some of the potential ramifications of their presence.

Though nitrogen, (N) is a very abundant element representing nearly eighty percent of the air we breathe, we need to monitor different forms of nitrogen in our drinking water. Both compounds, Nitrate, (NO3) and Nitrite, (NO2) are listed as primary contaminants by the United States Environmental Protection Agency which means they can have a negative impact on our health. We get nitrate and nitrite nitrogen in our water via many different potential sources such as poorly maintained wastewater treatment facilities, fertilizer, unlined manure piles, animal wastes (birds, fish, etc.), industrial wastes, and through decomposition. Huge pig farms in the Midwest and Southeastern U.S. can significantly impact water supplies if the waste is not properly stored. Overflows from storm and rain events can create infiltration of nitrates and nitrites into local streams, rivers, and water supplies with sometimes devastating effects. Nitrogen contamination from agricultural runoff is a main reason that farms are required to line their manure storage areas.

Nitrite is a fresh, or newly formed nitrogen compound. Because bacteria will quickly metabolize and convert nitrite to nitrate, we rarely find nitrite when analyzing drinking water in the lab. How can nitrite affect our health? Well, we all know there are nitrites in some of the foods we eat, but there is a good reason we don't want to drink water with high levels of nitrite - especially for pregnant women or infants. When nitrite comes in contact with the hemoglobin in our bloodstream it produces methemoglobin. Normally, hemoglobin transports oxygen via red blood cells throughout our bodies. Methemoglobin, however, prevents our red blood cells from carrying oxygen. If a pregnant woman drinks too much water with high levels of nitrite, or feeds it to her infant of three months or younger, she runs a risk of producing a condition called, "methemoglobinemia," or "blue baby syndrome." By significantly reducing the bodies ability to transport oxygen, it's no wonder where the condition gets its' name! Babies born with this condition come into the world looking like they're ready for an audition with the Blue Man Group! It's no laughing matter, however, because severe forms of this condition can be fatal. The maximum contaminant level, (MCL) for nitrite in drinking water is 1.0 mg/L (milligrams per liter). Milligrams per liter is the same as parts per million.

Nitrate nitrogen is often found in drinking water sources because of it's prevalence in the environment. Levels of nitrates are carefully monitored because too much in a lake or stream can rob or deplete the water of oxygen. High levels can kill fish as well as other organisms and cause significant change by turning the water anaerobic (without oxygen). The problem usually gets worse because nitrate is also a nutrient, or food source, which can feed algae creating conditions that are ripe for algae blooms. When a body of water has reached this point, it may be referred to as "eutrophic." Although we'll bring it up in another issue, the other major nutrient that often times comes into play in these scenarios is phosphorus.

We should be mindful of drinking water with too much nitrate, and one place we often forget to check is on the back of our favorite bottled water. Folks who rely on bottled water seem to have their favorites. Simply look on the back label and see what your water's nitrate level is. If it's not clearly stated, you can call, write, or email the bottling company and get the information. The U.S. Environmental Protection Agency sets the MCL for nitrate nitrogen in drinking water at 10.0 mg/L. Total combined nitrate and nitrite nitrogen levels may also not exceed 10.0 mg/L. I am neither discounting, nor advocating bottles water, however I can tell you that some bottled waters have nearly ten mg/L of nitrate in them. Maybe 10.0 is the maximum limit, but would you knowingly drink water with seven, eight, or nine mg/L of nitrate in it? (especially after reading this article?). Again, a simple on the label or phone call to the bottler will tell you where the level is for that particular brand.

Lastly, if you have a drilled well, it is not common to find very high levels of nitrate or nitrite nitrogen unless the aquifer or the well itself has been compromised directly by surface water. Dug wells, which are typically surface water sources are more susceptible to nitrogen contamination, especially after a significant rain event. There are other forms of nitrogen such as ammonia and organic nitrogen as well. Organic nitrogen, referred to as TKN, or Total Kjeldahl nitrogen is monitored in wastewater treatment facilities along with ammonia, (NH3). I have had some, shall we say, "exciting" moments in the lab when analyzing TKN. If the solution boils or refluxes to dryness, a rather significant exothermic reaction can occur - sometimes referred to as an explosion! That's why this analysis is run behind safety glass inside a vent hood approved for such a technique.

The best way to get nitrogen out of your drinking water is to remove the source of the nitrogen. If removal of the source of nitrogen is not possible or practical, methods such as reverse osmosis may be effective. As always, to check for nitrates and nitrites in your drinking water, you should have it analyzed by a laboratory certified for those parameters. For removal, consult with a water treatment professional for options that best fit your needs. I hope you have enjoyed this issue of Water Wisdom Tips and Newsletter, and thank you for reading. Cheers!