Nitrate Testing in Private Wells
Nitrate-nitrogen (referred to as nitrate) is a common contaminant found in many wells throughout Minnesota. Shallow wells, dug wells, and wells with damaged or leaking casings are the most vulnerable to nitrate contamination. Major sources of nitrate contamination can be from fertilizers, animal waste, and human sewage. Contamination is most often found in areas that have sandy or coarse soils, shallow bedrock, or karst geology. Areas with heavy row crop agriculture and vulnerable groundwater are especially at risk. It is highly recommended to test your drinking water supply on a regular basis.
Elevated levels of nitrate in drinking water can cause Blue Baby Syndrome in infants under six months of age and that are bottle fed. Nitrate can interfere with the blood’s ability to carry oxygen. Long term health effects to older children and normal healthy adults exposed to elevated levels of nitrate in their drinking water are not yet known or agreed upon in the scientific community. The Minnesota Department of Health has additional information about the health effects of Nitrate in Drinking Water.
Nitrate-nitrogen is a compound made up of nitrogen and oxygen. It can occur naturally in groundwater at levels typically in the range of 0 to 3 milligrams per liter (mg/L). Above 3 mg/L is considered elevated, and above 10 mg/L is considered unsafe.
There are two main options for testing your private well water for nitrate:
- Contact a certified water testing lab and follow their instructions for submitting a water sample. The Minnesota Department of Health has a searchable database to find an Accredited Laboratory.
- Contact your county Environmental Services or Soil and Water Conservation District (SWCD) or county and ask if they have access to a nitrate testing machine. The MDA loans nitrate testing machines to local partners so they can provide free nitrate analysis for private well owners. Water testing is provided at the local office or at a nitrate testing clinic (event).
If you are sending a sample to a certified lab, follow instructions provided by the lab. The instructions below are for collecting a sample to take to your local SWCD or county Environmental Services office or to a local nitrate testing clinic.
To take your sample, run your cold water tap for five to ten minutes then collect about one cup of water in a plastic baggie (double bag) or clean jar. Keep the water cool until arrival. You can collect the water anytime within one day of the nitrate analysis.
No. However, you may be asked to fill out a voluntary survey, but it is not required. The MDA does not record well owner information or results of individual water analyses.
Yes. Extra samples are free too. You are encouraged to test all the wells on your property (house, barn, irrigation, etc.). Also, you may collect neighbors’ or relatives’ samples and bring them in for analysis. If you have a water treatment unit that reduces or removes nitrate such as a reverse osmosis unit or a distiller, feel free to collect a sample before treatment and after treatment to ensure the treatment system is working properly. It is not necessary to collect a sample from before and after a water softener. A softener does not reduce nitrate, and the nitrate result will be the same before and after treatment.
The health risk limit for nitrate in drinking water is 10 mg/L, according to the U.S. Environmental Protection Agency (EPA) and the Minnesota Department of Health. If the sample has a nitrate concentration above 10 mg/L, it is critical that infants six months and younger do not drink this water in any form. Also, you should have your water re-tested at a certified water testing laboratory. The Minnesota Department of Health has a searchable database to find an Accredited Laboratory.
Options for well owners to reduce or remove nitrate vary depending upon type, age, and location of well. Drinking bottled water may be a good short-term solution. To figure out why you may have nitrate in your water supply, do some investigating. Look at your well record from when it was installed (your county may have this info.). Is your well fairly old? Does your well have construction problems? Is it a sand point, shallow, or hand dug? These well characteristics tend to commonly plague the owner with contamination problems. If you have concerns about your private well water, contact your county health department, a licensed well contractor, or your nearest Minnesota Department of Health district office.
There are water treatment units than can reduce the level of nitrate in your drinking water. However, they are an investment in both money and maintenance. Reverse osmosis, distillation, and ion exchange will reduce levels of nitrate significantly if the units are maintained properly. Keep in mind that these units can stop working at any time without your knowledge so test your water at least every year.
The other major contaminant to test for annually is bacteria. You can have this done at a certified water testing laboratory. Contact a certified water testing lab in your area to get a bacteria test kit. The Minnesota Department of Health has a searchable database to find an Accredited Laboratory.
Details of the Nitrate Clinic Water Testing Program
Through local partners such as SWCDs and counties, the MDA offers water testing clinics to increase public awareness of nitrate contamination in rural drinking water. Results from the testing are for the private well user’s personal use. Well owners/users may remain anonymous.
Nitrate clinics are developed for homeowner education and outreach and are not designed as a scientific study. If you would like to learn more about the MDA’s work assessing private well nitrate concentrations, please see our Township Testing Program.
The MDA provides the necessary equipment to local partners who can provide free water testing at the local office or locally organized events. The local partner is responsible for their own personnel to run the clinic and recording the nitrate analysis results.
