Drinking Water: Nitrate and Nitrite
What are nitrate and nitrite?
Nitrate and nitrite are molecules that are needed by plants and animals to live and grow.
Low levels of nitrate and nitrite can be found in fruits and vegetables, fish, dairy, beers, cereals, and cured meats. Nitrate is also naturally found in air, soil, and water at low levels.
Higher levels of nitrate and nitrite are sometimes found in surface water (lakes, rivers, and streams) and groundwater from human and animal waste and fertilizer use.
How can I be exposed to nitrate and nitrite?
The most common way people are exposed to nitrate and nitrite is through drinking water.
Nitrate is one of the most common groundwater contaminants in Wisconsin. Studies estimate that at least 10% of private wells in Wisconsin have high levels of nitrate.
How can nitrate and nitrite affect health?
Exposure to high levels of nitrate and nitrite can affect everyone.
In babies, nitrate and nitrite can cause blue baby syndrome (methemoglobinemia). This is a condition that affects how the blood carries oxygen leading to weakness, excess heart rate, fatigue, and dizziness.
Nitrate can increase the risk of neural tube defects – a type of birth defect that affects how the brain and spinal cord form. These defects occur very early in pregnancy often before a person even knows that they are pregnant. Nitrite may also cause these effects.
In all people, nitrate and nitrite may increase the risk of thyroid disease and may increase the risk of colon cancer.
How can I protect myself and my family from nitrate and nitrite?
Public water systems are required by the Wisconsin Department of Natural Resources (DNR) to test for nitrate and nitrite regularly.
Nitrate
If the level of nitrate is above Wisconsin's drinking water standard (10 milligrams nitrate-nitrogen per liter), the system will issue a do not drink advisory for sensitive populations.
If this happens:
People who are or may become pregnant should use immediately use a different source of water for drinking and making foods that take up a lot of water (like rice, oatmeal, and gelatin).
Options include bottled water, water from a public system without violations, and water from a private well without issues.
- Use different water for babies to drink and to make baby formula.
- It is ok to use the water for bathing, brushing teething, and washing dishes.
The DNR will work with your water system find a long-term solution.
Nitrite
If the level of nitrite is above Wisconsin's drinking water standard (1 milligrams nitrate-nitrogen per liter), the system will issue a do not drink advisory.
If this happens:
Everyone should use a different source of water for drinking and making foods that take up a lot of water (like rice, oatmeal, and gelatin).
Options include bottled water, water from a public system without violations, and water from a private well without issues.
- Also use different water for babies to drink and to make baby formula.
- It is ok to use the water for bathing, brushing teething, and washing dishes.
The DNR will work with your water system find a long-term solution.
Our Nitrite in Drinking Water fact sheet, P-02128a (PDF) has this information in a printable format.
Nitrate
Private well users should test for nitrate regularly using a Wisconsin certified lab.
- Test at least once a year.
- Also test before the water is used by someone who is or may become pregnant or it is given to a baby.
- Test right away if you notice a change in the color, taste, or smell of your water.
- Households with pregnant people and young children may be eligible for free testing through their local health department.
Take action if the nitrate level is equal to or greater than 10 milligrams nitrate-nitrogen per liter (mg/L):
People who are or may become pregnant should immediately use a different source of water for drinking and making foods that take up lot of water (like rice, oatmeal and gelatin).
Options include bottled water, water from a well without issues, and water from a public system.
- Use different water for babies to drink and to make baby formula.
- It is ok to use the water for bathing, brushing teething, and washing dishes.
- Retest your well to verify the results.
If the nitrate level is still high:
- Everyone should use an alternative source of water for drinking and preparing foods that take up a lot of water.
- Find a long-term solution. Options include installing a certified treatment device and drilling a new well.
- Our Water Treatment Devices for Private Well Contaminants fact sheet, P-45012 (PDF) has information on certified treatment devices for nitrate.
- The DNR's well compensation grants provide funds to address public health hazards in private wells.
Our Nitrate in Private Well Water fact sheet, P-02128 has these steps in printable format.
Nitrite
Private well users should test for nitrite if concerned about exposure.
- When testing, use a certified Wisconsin lab.
- Households with pregnant people and young children may be eligible for free testing through their local health department.
Take action if the nitrite level is equal to or greater than 1 milligrams nitrite-nitrogen per liter (mg/L):
People who are or may become pregnant should immediately use a different source of water for drinking and making foods that take up lot of water (like rice, oatmeal and gelatin).
Options include bottled water, water from a well without issues, and water from a public system.
- Use different water for babies to drink and to make baby formula.
- It is ok to use the water for bathing, brushing teething, washing dishes, and rinsing produce.
- Retest your well to verify the results.
If the nitrite level is still high:
- Everyone should use an alternative source of water for drinking and preparing foods that take up a lot of water.
- Find a long-term solution. Options include installing a certified treatment device and drilling a new well.
- Our Water Treatment Devices for Private Well Contaminants fact sheet, P-03494 (PDF) has information on certified treatment devices for nitrate. These devices will also work to remove nitrite.
- The DNR's well compensation grants provide funds to address public health hazards in private wells.
Our Nitrite in Drinking Water fact sheet, P-02128a has this information in a printable format.
Who regulates nitrate and nitrite in Wisconsin?
Nitrate is naturally occurring in the environment. The DNR regulates direct releases of nitrate into groundwater.
The DNR also regulates how much nitrate can be in water served by public water systems and establishes environmental requirements to limit runoff from fields, pastures and livestock facilities.
Related topics
Our groundwater standards page has information on how Wisconsin's groundwater standards are set, the Department of Health Service's role in the process, and a summary of the current and recommended standards, including nitrate and nitrite.
The DNR's information for private well owner's page has information on testing, finding well records, well abandonment, and more.
The Wisconsin Groundwater Coordinating Council's Annual Report to the Legislature summarizes the operations and activities occurring within the state to address groundwater issues including nitrate.
The University of Wisconsin - Steven Point Well Water Quality Interactive Viewer shows water quality data from a variety of contaminants (including nitrate) at a county, township, and section levels.
Questions? Can't find what you're looking for?
Contact us at dhsenvhealth@dhs.wisconsin.gov.