Michigan has one of the larger private-well populations in the country, spread across the state’s Lower and Upper Peninsulas. Private wells are not regulated under the federal Safe Drinking Water Act, and testing — including paying for it — is the well owner’s responsibility.
Why test
None of the common well contaminants below have a reliable taste, odor, or color at concerning levels, so a well can seem completely normal while still testing positive for a contaminant.
What to test for
A baseline panel for a Michigan well should include:
- Total coliform bacteria and E. coli — a standard first check for whether the well may be vulnerable to contamination.
- Nitrate — a concern in agricultural areas and near septic systems, and especially important for households preparing infant formula with well water.
- Arsenic — naturally occurring arsenic has been documented in groundwater in certain Michigan regions (notably parts of the state’s “Thumb” area); it has no taste or odor at concerning levels.
- Lead — mainly relevant to household plumbing rather than the source water.
- PFAS — Michigan has conducted extensive statewide testing and identified PFAS in groundwater near a number of contamination sites as part of its response efforts; if your property is near a known contamination site, a former firefighting-foam training area, or certain industrial or landfill sites, ask your lab specifically about adding PFAS to your test panel.
How often to test
EPA guidance recommends testing private wells for bacteria and nitrate at least annually, and again any time water quality changes noticeably, after well or plumbing work, or after flooding.
Where to find a certified lab
Michigan’s Egle (Department of Environment, Great Lakes, and Energy) Laboratory Certification Program certifies labs for drinking-water analysis, including dedicated statewide lists for chemistry, microbiology, lead and copper, and PFAS testing — see the source link above for the current certified-laboratory lists.
After you test
If a result comes back above a health-based guideline, see our filter guides for which technologies are certified to address that specific contaminant.