Nitrate in Drinking Water
Nitrate is a compound that naturally occurs and has many human-made sources. Nitrate is in some lakes, rivers, and groundwater in Minnesota. Consuming too much nitrate can be harmful—especially for babies.
Consuming too much nitrate can affect how blood carries oxygen and can cause methemoglobinemia (also known as blue baby syndrome). Methemoglobinemia can cause skin to turn a bluish color and can result in serious illness or death. Other symptoms connected to methemoglobinemia include decreases in blood pressure, increased heart rate, headaches, stomach cramps, and vomiting.
Bottle-fed babies under six months old are at the highest risk of getting methemoglobinemia. The following conditions may also put people at higher risk of developing methemoglobinemia: anemia, cardiovascular disease, lung disease, sepsis, glucose-6-phosphate-dehydrogenase deficiency, and some metabolic problems.
The U.S. Environmental Protection Agency (EPA) standard for nitrate in drinking water is 10 milligrams of nitrate (measured as nitrate-nitrogen) per liter of drinking water (mg/L).* Drinking water with levels of nitrate at or below 10 mg/L is considered safe for everyone in your family.
*One milligram per liter (mg/L) is the same as 1 part per million.
If you have a private well
Here are some recommendations on how to prevent and address nitrate contamination:
- Protect Your Well by constructing it in a safe spot.
- Regularly inspect your well for damage. Contact a Licensed Well Contractor if you find any.
- Test for nitrate every other year. You are responsible for keeping your well water safe and testing it as needed. All well testing should be done through an accredited laboratory. Contact a Minnesota Department of Health (MDH) accredited laboratory to get a sample container and instructions on how to submit a sample. You can also contact your county to see if they have any programs to make testing your water easier.
- Keep nitrate sources away from your well. Sources may include fertilizer, septic systems, and animal waste.
If nitrate is detected in your water, there may be other contaminants in the water as well. Drinking water with levels of nitrate above 10 mg/L can lead to immediate health problems for some people. If nitrate is detected in your water at levels above 10 mg/L, follow these steps:
- Get your drinking water from a safe alternative source.
- Make sure babies under six months old do not drink the well water.
- Do not try to boil nitrate out of the water. Boiling will make nitrate more concentrated in the water.
- Have your well inspected by a Licensed Well Contractor.
- Find and get rid of any potential sources of nitrate contamination. The Protect Your Well page can help you identify sources to check.
If you are on a public water system
Your public water system regularly tests for nitrate and ensures levels meet the EPA standard. You can find the level of nitrate detected in the system serving where you live by reading the system’s Water Quality Report (also known as a Consumer Confidence Report [CCR]). You can call your public water system to get a paper copy of your CCR, or you may be able to find it online at Find Your Local CCR. You can find the level of nitrate detected in the systems serving places other than where you live by contacting the water system.
Nitrate occurs naturally and at safe and healthy levels in some foods (such as spinach and carrots) and comes from natural processes, such as plant decay. Nitrate is used to preserve processed meats and is in many fertilizers used on yards, golf courses, and crops. Other sources of nitrate include discharge from sewage systems and animal wastes.
Natural processes can cause low levels of nitrate in drinking water—usually less than 3 mg/L. The health concern is with levels of nitrate over 10 mg/L. High levels of nitrate in water can be a result of runoff or leakage from fertilized soil, wastewater, landfills, animal feedlots, septic systems, or urban drainage. It can be difficult to pinpoint where the nitrate in drinking water comes from because there are many possibilities.
Nitrate has been detected in surface water and groundwater in many places in Minnesota. Land use and hydrogeology both affect the levels of nitrate found in water. MDH data show that about 3.6 percent of all private wells constructed in Minnesota since 1991 have nitrate levels above 3 mg/L. Levels above 3 mg/L suggest human-made sources of nitrate have contaminated the water. Most of the newly-constructed wells with nitrate levels above 3 mg/L are in central and southeastern Minnesota. Newly-constructed wells with levels of nitrate above 10 mg/L are concentrated in central and southwestern Minnesota.
The Minnesota Pollution Control Agency (MPCA) found that 27 percent of surface water samples had nitrate levels above 10 mg/L. Southern Minnesota had the highest levels of nitrate. You can read more at Report on Nitrogen in Surface Water.
There are a few public water systems in Minnesota that have detected nitrate levels above 10 mg/L in some treated water samples. You can learn more about nitrate levels in public water systems by visiting MN Public Health Data Access: Drinking Water Quality and MDH Drinking Water Protection Annual Reports .
MDH regulates public water systems by:
- Approving public water systems’ construction and treatment plans
- Enforcing the Safe Drinking Water Act
- Testing public water systems
- Requiring public water systems to protect water supplies from contamination (Source Water Protection Program)
MDH regulates private and public wells through:
- Establishing and enforcing Laws and Rules for proper Construction of Wells and Borings and Sealing of Wells and Borings
- Providing guidance for private well owners on Water Quality/Well Testing/Well Disinfection
MDH provides a dataset for Nitrate Risk to the Water Table Aquifer to inform drinking water protection efforts. MDH has monitored and quantified the risk of nitrate in drinking water through the Nitrate Exposure and Infant Risk Study (NEXIR) Study and the Volunteer Nitrate-Nitrogen (Nitrate) Monitoring Network Study.
MDA monitors and helps reduce nitrate from agricultural sources. Major efforts include private well Water Testing for Nitrate, Township Testing Program, Characterizing Nitrates in Private Drinking Water Wells, and the Nitrogen Fertilizer Management Plan.
Local government, including counties and Soil and Water Conservation Districts, help people manage nitrate from lawns, agriculture, and other sources. The best way to find out what resources and assistance are available to you is to type the local government unit name and nitrate in your internet browser.
MPCA released the Groundwater Protection Recommendations Report in 2016 that outlines ways to reduce nitrate and other contaminants in our water.