How Does Your Well Test?

The following was written by Katie L. Grant, communications director for the DNR.

Most residents don’t have to think twice about where their water will come from every day. Still, many lack reliable access to safe water — including some using a private well with poor water quality.

That’s why working to ensure access to safe, clean drinking water is a priority for the DNR and Gov. Tony Evers.

Nearly 30% of the state’s population gets its drinking water from private wells rather than municipal water systems, putting the responsibility largely on the homeowner. Private well owners are encouraged to have them regularly tested.


Everyone is potentially at risk from the three most common contaminants in Wisconsin well water, and well owners should test for these on a regular basis.

  • Bacteria: Test once a year, and when you notice a change in taste, color or smell.
  • Nitrate: Should test once a year, and before the well will be used by anyone who is or may become pregnant.
  • Arsenic: Test once. If arsenic was present in previous tests, then test once a year.


Additional testing may be helpful to look for naturally occurring contaminants in the rock and soil that could enter your well or if human-caused contaminants from land-use, plumbing materials or other sources of pollution may be near your well.

Manganese: If you notice brown or black staining in your home or black sediment in your water, test once for manganese.

Strontium: Consider testing for strontium if you live in the eastern or northern part of the state. Test twice over a two-year period in two different seasons, fall and spring being the best.

Fluoride: Test when you have a baby or when you move into a home with a well. Your dentist and pediatrician will use this information to decide how much additional fluoride to recommend.

Pesticides: Consider this test if your home is within a quarter mile of agricultural fields or areas where pesticides are manufactured, stored or mixed.

Lead and copper: Test once every five years, or if the water will be used by a pregnant woman or baby. Lead and copper may be in your water from the plumbing materials in your home.

Volatile organic compounds: Testing is recommended for homes within a quarter mile of a landfill, industrial site, gas station or other underground tank, and especially if you smell chemical or fuel odors in your home.

PFAS: Consider testing for perfluoroalkyl and polyfluoroalkyl substances if your well is near a known source of PFAS contamination or you have reason to believe PFAS may have been released near your well. Over 450 shallow private wells not near known PFAS contamination were sampled in 2022, and 99% were found to meet Wisconsin Department of Health Services recommended safety levels for PFAS.


Find additional information for private well owners at

For a list of certified labs to assist you in testing your private well, contact your local health department, go to