What is nitrate and where does it come from?
Nitrate is one form of dissolved nitrogen that occurs naturally in soil and water. It is the primary source of nutrients for plants and may be used as fertilizer. Once taken-in nitrates (NO3) turn into nitrites (NO2). Most natural concentrations are not a health concern to humans, but when excess nitrates get into water this can pose a problem for human health. Some human activities that introduce nitrates into water are fertilizing, runoff from animal feedlots, leaky septic tanks, industrial wastes and wastewater treatment lagoons.
What are some health concerns of nitrates in water?
Pregnant or nursing women and infants are especially vulnerable to nitrate related health problems. Nitrate can interfere with the ability of blood to carry oxygen in infants 6 months old or under. This is known as "blue baby syndrome". Infants may experience shortness of breath. Infants that receive formula mixed with well water with a high nitrate concentration level may have an increased risk of getting this syndrome. People over 6 years of age are not usually at risk for this syndrome because their digestive systems naturally absorb and excrete nitrates.
Little is known about the long term effects of drinking water with elevated levels of nitrates. However, there has been some research suggesting that nitrates may play a role in spontaneous miscarriages. Also, water sources that show nitrate contamination have the potential for other contaminants, such as bacteria and pesticides, which can reach groundwater along with nitrates.
How do I find out if there are nitrates in my water?
If you rely on a public water system, that water must meet state drinking water standards for nitrate. Water must be tested every year (quarterly if the result exceed the standard). If nitrate concentrations above the drinking water standard are found, the supplier is required to notify the public within 24 hours. Most water companies will send out an annual Consumer Confidence Report which discloses contaminants found, possible health effects and the water’s source. This report is generally sent in July with your water bill. If you do not receive a report, contact your water company for this information.
If you have a private water system (private well) then you are responsible to ensure your drinking water is safe for human consumption. You should test for nitrates at least once a year. To test for nitrates contact a certified testing lab near you. A nitrate test will cost approximately $14-30.
What is the drinking water standard for nitrates?
A nitrate level up to 3 parts per million (ppm) is generally considered naturally occurring and safe for drinking. The U.S. Environmental Protection Agency (USEPA) has set the primary drinking water standard for nitrates at 10 ppm. Concentrations that are significantly higher than the standard may be harmful to people and livestock. There is no standard for private well waters, nor is testing required, which means the private well owner is responsible for testing their own water.
What can I do to reduce nitrates in my drinking water?
The best way to reduce nitrate in drinking water is to identify potential sources of nitrate on your property (some common examples of this are faulty septic systems, fertilizers and animal wastes) and find ways to manage these systems. Also, check your wellhead to make sure it is properly located and has an effective seal.
Other ways to manage nitrates:
- If your water is contaminated with high levels of nitrate (10 ppm or above) infants and pregnant or nursing women should not drink the well water. If you are using infant formula, use bottled water or use pre-mixed formula.
- Reverse osmosis, distillation, or ion exchange systems can all be used to remove nitrates. However, these systems can be expensive and require careful maintenance to operate effectively. For more information on these systems see the fact sheet Drinking Water Treatment Systems.
- Do not boil water to remove nitrates. Boiling water will concentrate nitrate, not remove it. Charcoal filters, water softeners, or use of chlorine will not remove nitrates from water.
- If excessive nitrate concentration is found, monitor nitrates at leas twice a year (once in the winter and once in the summer) and keep records.
- Water with a high nitrate concentration may not be safe to ingest, but it can be safely used for bathing, laundry, cleaning dishes, or other uses where water is not ingested.
- High levels of nitrates may signal the presence of other contaminants, like pesticides and disease causing bacteria. Examine your property, as well as the surrounding area, for sources of contaminants. Consider testing for other chemicals if you think your water is at risk. For more information on possible contaminants see our webpage Risks To Your Water.