Well Testing, Results, and Options - EH: Minnesota Department of Health

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.

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
  1. Get your water from a safe alternative source (like bottled water) until you address the problem. If nitrate is not detected in your water, you can also boil your water before using it for drinking or cooking.
  2. Disinfect your well and water system with a chlorine solution (see Well Disinfection instructions or hire a licensed well contractor to disinfect your well).
  3. Test your water again after disinfecting the well and water system.
Nitrate The level is above 10 mg/L*
  1. Get your water from a safe alternative source (like bottled water) until you address the problem. Do NOT boil the water—boiling will increase the nitrate concentration.
  2. Do not give the water to infants under six months old.
  3. Have a licensed well contractor inspect and repair your well.
  4. Remove potential sources of nitrate near your well.
  5. Consider home water treatment if you have completed steps 3 and 4 and no infants drink the water.
  6. Test your water again after taking action.
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**
  1. Consider home water treatment or using a different drinking water source. Before you pay for home water treatment, it may be good to confirm the arsenic level.
  2. Test your water again after taking action.
Lead Any level of lead is harmful.
  1. Let the water run 30-60 seconds before using it for cooking or drinking.
  2. Use cold water for drinking and cooking.
  3. See if you can find out what the source of lead may be in your plumbing system and consider replacing that part of the system.
  4. Consider getting a pitcher filter or home water treatment if your water still has high levels of lead after you let the water run.
  5. Test your water again after taking action.
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**
  1. Use an alternative water source when using water to make formula or juice for a baby.
  2. Consider getting a pitcher filter or home water treatment.
  3. Test your water again after taking action.

*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

Learn More About Water Treatment Options


Well Management Section
651-201-4600 or 800-383-9808

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Updated Tuesday, 16-Aug-2022 19:15:30 CDT