Nitrates and Nitrites in Drinking Water

Nitrogen can take different forms in nature and is important for life in both plants and animals. The most common form of nitrogen found in well water is nitrate. Nitrate contamination of water usually comes from fertilized agricultural fields, septic system failures, or compost piles that are too close to wells.

Wells with high levels of nitrates are more likely to be privately owned and/or shallow and affected by human activity. If human or animal waste contaminates a well, nitrites will be detected first but will quickly convert to nitrates. Therefore, most well water tests are done for nitrates.

The Health Department recommends testing your private water source for nitrates and other contaminants. Find out what you should test

The maximum contaminant level for nitrates in water is 10.0 mg/L and for nitrites is 1.0 mg/L. Actions to remove or reduce nitrates should be taken if levels exceed 5.0 mg/L

Health Effects of Nitrates and Nitrites in Drinking Water

There are two health concerns when drinking water with high levels of nitrates or nitrites.

The first is risk of “blue baby syndrome,” also called methemoglobinemia:

  • Poisoning can occur when babies drink formula made with nitrate- or nitrite- contaminated tap water.
  • The baby’s blood is less able to carry oxygen due to the poisoning.
  • Affected babies develop a blue-gray color and need emergency medical help immediately.
  • Babies under six months of age are more at risk.

The second is the potential formation of chemicals called nitrosamines in the digestive tract. Nitrosamines are being studied for long-term links to cancer. No standards have been set for this yet.

Treatment Options

Treatment methods such as anion exchange and reverse osmosis can remove nitrates from drinking water.

Anion exchange uses equipment and technology similar to a water softener. It treats all the water for the home. The nitrates are removed from the water as they are exchanged for (harmless) chlorides. The chlorides are supplied from a salt tank which must be re-filled on a schedule.

Reverse osmosis uses a membrane through which water (but not nitrates) can travel. The system is typically installed beneath the kitchen sink with a small tank holding the nitrate-free water. Water used for drinking and food preparation comes from this tank under the sink. If the well water is hard or contains too much iron, a softener or iron removal system must be installed before using the reverse osmosis system.

Call a water treatment professional for details. Do a follow-up nitrate water test to make sure the treatment worked and nitrates are not present. We strongly recommended properly maintaining the treatment system and periodic testing for nitrates to make sure the system is working.

Financial Assistance: Is there funding available to help me pay for my water system or treatment?

Vermont Wastewater and Potable Water Revolving Loan Fund

This program, also known as the On-site Loan Program, is available to certain Vermont residents for the repair or replacement of failed water supply and on-site wastewater systems. The On-site Loan Program is funded and administered by the Agency of Natural Resources, Department of Environmental Conservation with loan underwriting and servicing provided by the Opportunities Credit Union in Winooski. Your drinking water supply has to be a failed system and you must be living in the residence on a year-round basis to be eligible. The family income cannot exceed 200% of the state median household income. For more information about eligibility and how to apply, call 802-461-6051 or visit the website.

The NeighborWorks Alliance of Vermont

The NeighborWorks Alliance is made up of five local organizations offering full affordable housing services for income-eligible individuals. You may qualify for help from this program if you need money to install a water treatment system, drill a well, or repair or replace your septic system. For more information on eligibility, contact the local NeighborWorks HomeOwnership Center in your region.

Single Family Housing Repair Loans and Grants

This program offers loans and grants to exiting homeowners for well construction, repair and sealing. It's administered by the Rural Development office of the U.S. Department of Agriculture. The program is for low-income families who live in a rural area or a community with a population of 25,000 or less. The family income cannot exceed 50% of the median county income. Individuals who are 62 years of age or older may qualify for a grant or a combination of a loan and grant. Younger applicants are eligible only for loans.

Burlington, South Burlington, Essex Junction, Winooski and parts of Colchester are ineligible for the program because of population. Even if your property is in an eligible area, your eligibility is still subject to income limits. For more information or to find out if your property is in an eligible area, call 802-828-6022 or visit the website.