What are they?

Nitrates and nitrites are compounds that are commonly used in lawn treatments and fertilizers, and have been for many years. Nitrogen compounds are essential nutrients for plants, which take them from the soil. Crops may eventually deplete these nitrogen compounds from the soil, making it harder to grow additional crops in the future. The soil is treated with nitrogen-based fertilizers, and plants may continue to grow vigorously in this enriched environment. The use of fertilizers and lawn treatments can invade wells, and contaminate the well water. 

Nitrate and nitrite in the soils, not surprisingly, also seep into groundwater supplies, with shallow wells and groundwaters containing much higher levels than deeper water that are not in contact with the surface soils. 

Why should I be concerned?

Nitrites can cause problems in young children and farm animals, as they bind very strongly to hemoglobin, and can affect the blood's ability to carry and release oxygen. Nitrates are ingested - through water, or food - and nitrate-reducing bacteria in an infant's digestive tract convert these nitrates to nitrites. These nitrites find their way to the circulatory system, and bind very tightly with hemoglobin, which is the component of the blodd that attaches to oxygen in the lungs, and releases oxygen to the body tissues that need it. If the nitrites bind to hemoglobin, it is practically useless for oxygen transfer; causing shortness of breath, increased susceptibility to illness, heart attacks, and even death by asphyxiation in extreme cases. As a child develops, the acidity of the stomach becomes stronger, and the nitrate-reducing bacteria are killed. Nitrates are not usually a problem for older children and adults. 

How can I tell if my water has nitrates in it?

The surest way to tell is by having your water tested. Use a reputable lab - either run by your County Health Department, or certified by state authorities. 
 

What can I do about it?

Water found to contain excessive nitrates can be treated by a variety of methods. Point-of-Use systems reduce the levels by either Reverse Osmosis filtration, Distillation, or a disposable mixed-bed deionizer - and can remove the nitrates (and other contaminants) for water specifically to be used for drinking and cooking. Another option is a system very much like a water softening system, using a strong base anionic exchange resin bed rather than the cationic exchange resin bed commonly used for water softening. It is regenerated in a similar way to conventional softeners. This system is most effective in tandem with a water softening system, and provides a whole-house removal solution. 

Many communities with a municipal water treatment system split off a portion of the water, and treat it to remove nitrates. This purified water is blended into the general water supply, effectively diluting the nitrate levels to below standards. Consumers especially concerned with nitrate levels may still prefer to use a Point-of-Use system to remove remaining nitrates. 
 

Glossary Definitions: Methemoglobinemia