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Environmental Health Division
Well Testing, Results, and Options
As a private well owner, you are responsible for regularly testing the water you use for cooking and drinking to make sure it is safe. The Minnesota Department of Health (MDH) recommends that you test water from a faucet that you use for cooking and drinking and that you test for the contaminants in the table below. If you treat your water, test the water after it goes through treatment. Testing for all of the contaminants below is especially important if babies or young children drink the water (see Safe Drinking Water for Your Baby).
Well Testing, Results, and Options information sheet by language:
|How Often a Well Should be Tested
|Coliform bacteria can indicate that other infectious bacteria, viruses, or parasites may be in your water. These may cause diarrhea, vomiting, cramps, nausea, headaches, fever, and fatigue.
|Test for nitrate every year
|Consuming too much nitrate can affect how blood carries oxygen and can cause blue baby syndrome. Bottle-fed babies under six months old are at the highest risk of being affected by nitrate. Blue baby syndrome can result in serious illness or death.
|At least once
|Consuming water with even low levels of arsenic over a long time is associated with diabetes and increased risk of cancers of the bladder, lungs, liver, and other organs. Ingesting arsenic can also contribute to cardiovascular and respiratory disease; reduced intelligence in children; and skin problems such as lesions, discoloration, and the development of corns. Health impacts of arsenic may take many years to develop.
|At least once
|Lead can damage the brain, kidneys, and nervous system. Lead can also slow development or cause learning, behavior, and hearing problems. While lead can affect everyone, babies, children under six years old, and pregnant women are at the highest health risks from lead.
|At least once before a baby drinks the water
|Manganese can cause problems with memory, attention, and motor skills. It can also cause learning and behavior problems in infants and children.
Both natural sources and human activities can contaminate well water and cause short-term or long-term health effects. Testing your well water is the only way to detect most of the common contaminants in Minnesota groundwater; you cannot taste, see, or smell most contaminants.
You may also want to test for other contaminants if you have other water quality concerns or live in an area of known groundwater contamination. Learn more about private well water quality topics at Water Quality/Well Testing.
Learn More About the Contaminants Mentioned Above
Contact an accredited laboratory to get sample containers and instructions, or ask your county environmental or public health services if they provide well water testing services. After the laboratory analyzes your water sample, the laboratory will send you a report with the test results.
Find an Accredited Water Testing Laboratory
MDH accredits laboratories to ensure they use methods and standards that will give you accurate information about your water quality. Below are two tools to find an accredited laboratory. MDH recommends contacting a few laboratories to compare costs.
- Accredited Labs in Minnesota Accepting Samples from Private Well Owners (PDF): This map and table show MDH accredited laboratories in Minnesota that accept samples from private well owners and are certified to test for arsenic, coliform bacteria, lead, manganese, and/or nitrate.
- Search for Accredited Laboratories: You can search for all MDH-accredited laboratories in the United States.
- Select the Customized Searches tab; for "Program" select Safe Drinking Water Program; then select the analyte (contaminant) to be tested.
- At the bottom of the page check the box that says Accepts samples from private homeowners and click on Search.
- The resulting list are labs that are certified to test for that contaminant.
Each laboratory may list your test results differently. The table below lists the main contaminants MDH recommends you test for, the level of the contaminant that can be harmful in your drinking water, and what you can do to protect your household’s health. Please contact the laboratory or MDH with questions about your results.
|Drinking Water can be Harmful if:
|What to do if There is an Unsafe Level of a Contaminant
|Any coliform bacteria are detected
|The level is above 10 mg/L*
|Any level of arsenic may be harmful. MDH highly recommends taking protective action if the level of arsenic in your drinking water is above 10 µg/L**
|Any level of lead is harmful.
For babies under one year old: The level of manganese is above 100 µg/L**
For everyone else: The level of manganese is above 300 µg/L**
*mg/L=milligrams per liter and is the same as parts per million (ppm)
**µg/L=micrograms per liter and is the same as parts per billion (ppb)
- Home Water Treatment: General treatment options.
- Water Treatment Units for Arsenic Reduction (PDF).
- Grants and Loans for Home Water Treatment and Well Construction, Repair, and Sealing: Grants and loans to help cover the cost of installing a home water treatment unit.