Nitrates & Nitrites in Tap Water

Nitrates (NO3-) and nitrites (NO2-) are chemical compounds that contain nitrogen and oxygen. They can naturally occur in the environment, but elevated levels in tap water are often associated with human activities, particularly agriculture and the use of fertilizers.

Sources of Nitrates and Nitrites

Agricultural Runoff: The excessive use of nitrogen-based fertilizers in agriculture can lead to the leaching of nitrates into groundwater, which may eventually find its way into tap water sources.

Septic Systems: Malfunctioning or inadequately maintained septic systems can release nitrates into the soil and groundwater.

Landfills and Wastewater: Landfills and wastewater treatment facilities can also contribute nitrates to the environment, although these sources are usually managed to prevent contamination of drinking water sources.

Health Concerns

Excessive levels of nitrates and nitrites in tap water can pose health risks, particularly for vulnerable populations:

Infants: The most significant concern is for infants under six months old. When infants consume formula prepared with tap water containing high levels of nitrates, it can lead to a condition called "methemoglobinemia" or "blue baby syndrome." This rare but serious condition reduces the blood's ability to carry oxygen, causing a bluish tint to the skin and potentially life-threatening oxygen deprivation.

Pregnant Women: High nitrate levels in drinking water can pose risks to pregnant women, potentially affecting fetal development.

Adults: While the risks are highest for infants, long-term exposure to high nitrate levels in drinking water has been associated with certain health concerns in adults, including an increased risk of gastric cancer.

Regulation and Monitoring

To protect public health, regulatory agencies like the Environmental Protection Agency (EPA) in the United States have established strict standards for allowable levels of nitrates and nitrites in drinking water. Water utilities are required to regularly monitor and test for these contaminants to ensure compliance with safety standards.

Treatment and Removal

Water treatment plants may use ion exchange, reverse osmosis, or other methods to remove nitrates from tap water when levels are elevated.

Preventive Measures

Preventive measures include proper disposal of household chemicals, careful use of fertilizers, and regular inspection and maintenance of septic systems to prevent contamination of groundwater.


While tap water in the United States is generally safe, nitrates and nitrites in drinking water can pose health risks, especially for infants. Regulatory standards, water quality monitoring, and effective treatment processes are crucial for ensuring the safety and quality of tap water. If you have specific concerns about nitrates and nitrites in your tap water, you can request water quality reports from your local water utility for information on contaminant levels in your area.