The US Environmental Protection Agency has established a standard for nitrate as nitrogen in drinking water under the Safe Drinking Water Act of 10 mg/L nitrate-nitrogen (also referred to as parts per million). This level was set in order to prevent cases of methemoglobinemia, a condition also known as blue baby syndrome, where an infant's blood cells carry nitrogen instead of oxygen. This condition may occur in infants under six months of age that are exposed to high levels of nitrate in drinking water because their gastrointestinal systems are not fully developed. High levels of nitrate in drinking water have also been implicated in miscarriages in certain areas of the nation where the water supply has been affected.
The safe drinking water standard of 10 mg/L of nitrate-nitrogen does not necessarily mean that exposure to lower levels is safe. Ongoing research indicates possible links between long-term consumption of drinking water with low levels of nitrate and certain types of cancer and the incidence of Type 1 diabetes in children. Some other emerging research shows potential links between other sources of nitrates and nitrites in the diet in the form of preservatives and other compounds in processed meats. More research is needed to fully prove the relationship between these diseases and the consumption of low levels of nitrates in drinking water but homeowners may want to keep informed on the nitrate levels in their private wells.
How do I read a water test report?
When your report comes back from the lab, the nitrate concentrations can be reported either as nitrate (NO3) or as nitrate-nitrogen (NO3 -N). Be sure to know which reporting system is being used because the concentrations of each are considerably different. If the lab reports its results as nitrate-nitrogen (NO3-N), the drinking water quality standard is 10 milligrams per liter. The standard is 45 milligrams per liter if the results are reported as nitrate (NO3). A milligram per liter (mg/L) is also equal to a part per million (ppm) in water analysis. If you are unsure of how to interpret the report, contact the lab, the local Extension office, or health department. It is important to check the lab report carefully because the two systems of reporting are frequently interchanged and can lead to confusion.
What does Oregon rule say?
Neither Oregon nor the US Environmental Protection Agency sets standards for private drinking water wells like the 10 mg/L standard. However, the state is concerned about ensuring that users of private wells benefit from safe drinking water supplies, like users of regulated public water systems. As a result, Oregon established a groundwater quality protection standard of 7 mg/L nitrate-nitrogen to trigger action when the groundwater quality shows signs of declining.