New Jersey Environmental Public Health Tracking Program

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Nitrate in Drinking Water

What is Nitrate?

Nitrate is a nitrogen compound that occurs naturally in soil, water, plants, and food. Nitrate is formed when microorganisms in the environment break down organic materials, such as plants, animal manure, and sewage. Nitrate can also be found in chemical fertilizers.  

Nitrate can get into drinking water from runoff or seepage into groundwater or surface water from farms, golf courses, home lawns and gardens.  Other sources of nitrate in water include landfills, poorly managed animal feedlots, and faulty septic systems.

How Does Nitrate Affect Human Health?

Under certain conditions, the body changes nitrate into a related compound, nitrite. Methemoglobinemia, a form of anemia, can result from the reaction of nitrite with hemoglobin in the blood. When this occurs, the ability of the blood to carry oxygen to the body's tissues is decreased. In infants, this condition is one of the causes of "blue baby" syndrome.  Infants are especially susceptible for four reasons:

  1. their fluid intake per body weight is greater than that of adults;
  2. their stomach acidity can be lower than adults, thus allowing the growth of stomach bacteria that change nitrate into nitrite;
  3. they have a form of hemoglobin that is more likely to form methemoglobin; and
  4. they are less able to change methemoglobin back into normal hemoglobin.  Pregnant women are also more susceptible to nitrate-induced methemoglobinemia since they have higher than normal levels of methemoglobin. 

Nitrite can react to form a variety of N-nitroso compounds by reacting with proteins in the stomach.  Some of these compounds have been found to cause cancer in animals.  However, according to the U.S. Environmental Protection Agency (USEPA), there is not enough information to determine whether exposure to nitrate and nitrite in drinking water can result in human cancer.

What is Being Done to Protect Human Health?

The USEPA has set the Maximum Contaminant Level (MCL) for nitrate in drinking water at 10 milligrams per liter (mg/L).  Since this standard takes available health effects information into account, infants are unlikely to develop methemoglobinemia caused by drinking water if the water contains nitrate at or below this level.  NJDEP requires the more than 600 public community water systems and 900 non-transient non-community water systems in New Jersey to monitor periodically for nitrate and to comply with the MCL.

The NJ Department of Environmental Protection Private Well Testing Act requires wells in all New Jersey counties to be tested for nitrate at the time of property transfer and also requires landlords to test private wells and provide tenants with the results.

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