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Home > Protecting Our Lands & Waters > Water Protection > Private Well Testing for Pesticide Contamination > Private Well Contamination Risks

Private Well Contamination Risks


In Minnesota private well owners are responsible for testing their wells and for their own drinking water safety.  This makes it necessary to be familiar with circumstances and conditions that could cause your private well to be at risk for contamination.

Contamination Risks

Ground Water Contamination Susceptibility in Minnesota. Source: MPCA 1989Geological risks:

  • Wells that are in areas of the state with soils and geology that are susceptible to contamination such as the central sand plains or the karst region in southeast Minnesota are more at risk for contamination.  The central sand plains and the karst region as well as other geologically susceptible areas are shown in red on the ground water contamination susceptibility map.  To find out information on the soil types in your area go to the United States Department of Agriculture Web Soil Survey.

Risks involving the well:

  • Wells that are more at risk for contamination are:
    • Dug, drive point and bored wells.
    • Old wells that have not been properly maintained.
    • Wells built before 1974 when Minnesota adopted and began to enforce rules concerning well construction.
    • Shallow wells that are less than or near to 50 feet in depth.
    • Wells that have been damaged.
    • Wells that have had their well head submerged because of flooding.
    • Wells located near to a chemical spill. 
    • Wells that do not meet isolation setback requirements.  Isolation distances and other information concerning protecting your well can obtained from the Minnesota Department of Health’s (MDH) Protecting Your Well web page and Well Owner’s Handbook.

Signs that your well water could be contaminated:

  • A change in the color, taste, smell, clarity, or feel of your water could indicate the contamination of your well water.  For guidance on what a change in your well water could indicate and other information on well safety and maintenance refer to the Environmental Protection Agency’s (EPA) Drinking Water from Household Wells brochure and Frequently Asked Questions web page.

Contaminants: Their Health Threats and How to Check For Them

  • For information about certain contaminants health threats and how to check for them visit the MDH Water Contamination and Your Health web page. 
  • For a list of contaminants, their health threats and their health risk limits (HRL) or the levels above which they are considered negative to your health.  Visit the MDH Groundwater Values Table web page.
  • For information on testing for pesticides, visit the Minnesota Department of Agriculture’s Testing for Pesticide Contamination web page.

What to Do About a Contaminated Well

If your well water is contaminated, try to stop the source of the contamination if possible and or treat your water.  For information on home water treatment devices consult the MDH Home Water Treatment Unites web site.  For information other information on home water treatment devices and what the devices will treat for consult the Iowa Hygienic Laboratory’s Water Quality and Home Water Treatment brochure.  Make certain the devices are certified by the Water Quality Association, the National Science Foundation or the Underwriters Laboratory.