The best protection against contaminants harming your family’s water supply is having an annual checkup of your water well system. Additional tests are suggested in special circumstances – floods, heavy rainfalls, known chemical spills – to ensure that you always have safe drinking water.

Contamination from nitrates is one of the problems that can arise after severe flooding or heavy rains in rural areas.

Nitrates are nitrogen-oxygen chemical units that combine with various organic and inorganic compounds, or may be present in water in ionic form. They are essential nutrients for plants, which absorb them from soil. The excess nitrates not used by the plants are carried through the soil to ground water in a process called “leaching.” Once in water, they remain there until used by plants or another organism, or removed by water treatment techniques. The occurrence of nitrogen compounds in soil and water is very complex.

The greatest source of nitrates in water in the USA is fertilizers that are used to provide nitrates to crops. Animal and human waste also contains nitrogen in the form of ammonia. This may oxidize to the nitrite and nitrate nitrogen ion forms. Decomposing plant and animal materials also generate nitrates.

The U.S. Environmental Protection Agency has set a maximum contaminant level for nitrates at 10 parts per million. High levels of nitrates can cause health problems, including methemoglobinemia, commonly known as “blue baby syndrome.”

In blue baby syndrome, nitrates are reduced to nitrites by bacteria in an infant’s stomach. When the nitrites enter the bloodstream, they interfere with the blood’s ability to carry oxygen to body tissues. This can be an acute condition in which the baby’s health deteriorates rapidly in a span of a few days. It can cause shortness of breath, increased susceptibility to illness, heart attacks, and even death by asphyxiation.

Older children and adults are able to withstand higher levels of nitrates than babies because of stronger stomach acids that kill the bacteria. However, there have been reports that nitrates could potentially be linked to gastrointestinal cancer. The EPA also says that long-term exposure to water over the maximum contaminant level can cause diuresis (excessive discharge of urine), increased starchy deposits, and hemorrhaging of the spleen.

The presence of significant levels of nitrite and nitrate may indicate additional groundwater contamination conditions, which should be investigated and addressed. Some nitrate-reducing bacteria are known to form heavy growths on well screens and equipment. Excessive nitrate in groundwater feeding ponds and streams contributes to algal growth and oxygen depletion, affecting aquatic life.

Nitrates are very soluble, and do not bind with soil so the potential is high for them to migrate to ground water. This is especially true if your water well system is near agricultural land or animal feed lots. The only preventive factors are clays that limit groundwater flow and deep chemically reductive zones that convert nitrate back to ammonia and nitrogen gas. Incidents such as heavy rains, flooding, chemical spills, or failed sewage systems can cause nitrates to enter soil near your private water well, too.

The one way to know for sure is to have your water tested because nitrates are tasteless and odorless. Water should be tested for the nitrite and ammonia forms also. This is best done by laboratory analysis, but onsite testing can be used for a preliminary result. Consult a hydrogeologist, environmental health professional, or qualified licensed and/or certified ground water contractor (find National Ground Water Association-member and certified contractors at the Contractor Lookup on this web site) or consult the EPA certification officer in your state for EPA-certified labs in your area to test your water supply.

No, because nitrates don’t evaporate. In fact, boiling will increase the concentration of nitrates in water.

Water containing nitrates can be treated by a variety of methods. The EPA has approved certain methods for removing nitrates and nitrites, including reverse osmosis and ion exchange.

Methods such as reverse osmosis or a disposable mixed-bed deionizer work best on point-of-use systems (installed in places such as the kitchen sink where water is mostly used for drinking or cooking). Ion exchange, used along with a water softening system, can provide a whole-house solution for nitrate contamination. Biological nitrate-reduction systems are also available and effective at the whole house or even village scale.

The best solution is the removal of the source of excessive nitrate. Stop it at the source. This is groundwater contamination.

Consult a hydrogeologist, local environmental health professional, or qualified licensed and/or certified ground water contractor for more information. A listing of NGWA-member and certified groundwater contractors is available on this web site.

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