Nitrate Information

Nitrogen is an essential part of every living thing. Nitrate-N is formed when nitrogen combines with oxygen or ozone. However, nitrate-N easily dissolves in water and does not adhere to the soil which allows it to be easily carried into groundwater, making it one of the most common groundwater pollutants in Portage County and across the state of Wisconsin.

Low levels of nitrate-N (below 1 mg/L) can occur naturally in groundwater. However, elevated levels of nitrate-N are indicative of impacts from human land use. The WGCC (Wisconsin Groundwater Coordinating Council) report states approximately 90% of all nitrate-N inputs to groundwater originate from agricultural sources, 9% from septic systems, and 1% from lawns or other sources. While nitrate-N contamination of drinking water can be found throughout the state, there are certain areas that are more susceptible due to naturally occurring geology and human land uses.

To learn more about the Nitrate-N in drinking water, visit the Wisconsin Department of Health Services Website.

Since nitrate-N does not smell, taste, or have any color, the only way to know for certain if it is present in your private well is to have it tested by a state-certified water laboratory. Professionals recommend that your water be tested at least annually for nitrate-N and bacteria.

Periodically the Portage County Water Resource Specialist will conduct Nitrate Screening Events throughout the County. These screening events are opportunities for residents to bring in a water sample and have it screened free of charge for nitrates. The screening, while not a certified lab test, will offer residents an idea of what the nitrate-N concentration is in their drinking water.

If your well tests above 10 mg/L nitrate-N, do not boil your water! Boiling water increases the nitrate-N concentration in the water. Instead, switch to bottled water if there is an infant, small child, pregnant woman, or woman of childbearing age in your home. Elevated nitrate-N concentrations are only a concern for water that is being consumed or used in the cooking of food and beverages to be consumed. It is not a concern for daily tasks such as dishwashing, laundry, bathing, etc.

To deal with elevated nitrate-N concentrations long term there are three options:

• Bottled Water
• Treatment System - There are a variety of treatment systems available to homeowners to treat water quality issues. Common types of treatment systems for the removal of nitrate-N include reverse osmosis, distillation, and anion exchange. These systems can range from a single point-of-use system to whole-home treatment.
• New Well - Private well owners may consider installing a new well to try and achieve better water quality in their private well. However, there is no guarantee that by installing a new well a private well owner will reach better quality of water.