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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. 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).
What to test your well water for
| Contaminant | How Often a Well Should be Tested | Health Impacts |
|---|---|---|
| Coliform Bacteria | Every year | 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. |
| Nitrate | Every other year | Bottle-fed infants under six months old are at the highest risk of being affected by high levels of nitrate in drinking water. High levels of nitrate can affect how blood carries oxygen and can cause a serious illness called methemoglobinemia (also known as blue baby syndrome), which can result in death. |
| Arsenic | At least once | Drinking water with arsenic in it for a long time can contribute to reduced intelligence in children and increased risks of cancer, diabetes, heart disease, and skin problems. |
| Lead | At least once | Lead can damage the brain, kidneys, and nervous system. Lead can also slow development or cause learning, behavior, and hearing problems. Babies, children under six years old, and pregnant women are at the highest health risks from lead. |
| Manganese | At least once before a baby drinks the water | High levels of 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. Learn more about private well water quality topics at Water Quality/Well Testing.
Learn More About the Above Mentioned Contaminants
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How to test your well water
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 the most 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. MDH reviews and updates this map each year.
- Search for Accredited Laboratories: You can search all MDH-accredited laboratories in the United States.
What your test results mean and next steps
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.
| Contaminant | Drinking Water can be Harmful if: | What to do if There is an Unsafe Level of a Contaminant |
|---|---|---|
| Coliform Bacteria | Any coliform bacteria are detected |
|
| Nitrate | The level is above 10 mg/L* |
|
| Arsenic | 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** |
|
| Lead | Any level of lead is harmful. |
|
| Manganese | 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)
Additional Information
- Bacterial Safety of Well Water (PDF).
- Nitrate in Well Water (PDF).
- Arsenic in Well Water (PDF).
- Lead in Well Water Systems (PDF).
- Manganese in Drinking Water
Learn more about water treatment options
- 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.
Questions
Well Management Section
651-201-4600 or 800-383-9808
health.wells@state.mn.us
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