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Private wells in Wisconsin
Wisconsin doesn't require a well inspection or water test when a home is sold. If one is done, though, state rules say who does it and what it covers. Here's what that means for buyers, what statewide test data show, and where to find labs, well records and help paying for a new well. Every fact has a source.
Wisconsin at a glance
- Who's on a well: USGS estimates about 1.6 million Wisconsin residents supplied their own household water in 2015, about 28% of the state's population.1 The Wisconsin Department of Health Services (DHS) says about 900,000 homes, roughly 4 in 10, are on private wells.2
- Home sales: no state-required test or inspection. Inspections that are done must follow DNR rules (see below).3
- DNR's advice: test for bacteria and nitrate every year, and arsenic every five years. In Brown, Outagamie and Winnebago counties, DNR recommends testing for arsenic every year.4
County pages
- Well water testing in Waukesha County, WIWaukesha County's state-certified well water lab, well and septic evaluations for home sales, what USGS and UW-Stevens Point data show for nitrate, arsenic and herbicides, DNR rules for buyers, and contacts, with sources.
Wisconsin counties with the most people on household wells in USGS's 2015 estimates are Waukesha (about 132,000), Dane (about 75,000), Kenosha, Washington, Marathon and St. Croix (about 43,000–50,000 each).1 We're adding pages for these counties.
Buying a home with a well in Wisconsin
What's required. Wisconsin DNR says state law doesn't require a well inspection or water test when property is sold. Some lenders require one.3
If an inspection is done (since June 1, 2008), DNR says:3
- it must be done by a licensed well driller or pump installer, on DNR's property transfer well inspection form (3300-221);
- the inspector must sample for coliform bacteria, nitrate and arsenic (irrigation wells: coliform only);
- the inspector must look for unused wells on the property, which must be properly filled and sealed.
Fixing problems. DNR says there's no requirement to bring a well into compliance at sale. The buyer and seller negotiate, and a lender may require fixes. DNR's fact sheet DG-092 explains inspection results.3
Seller disclosure. Wisconsin's Real Estate Condition Report (Wis. Stat. § 709.03) asks the seller about defects in the well, including unsafe well water due to contaminants such as coliform, nitrate or arsenic.5
See our homebuyer's guide for contingencies, flow tests and negotiating.
Contaminants to know about
DHS reviewed private well tests from 1988 to March 2017:2
| Test | Tests over the standard |
|---|---|
| Coliform bacteria | 16% of 79,579 tests positive |
| Nitrate | 10% of 73,517 over 10 ppm |
| Arsenic | 3% of 14,699 over 10 ppb |
DHS says arsenic is most common in parts of Florence and Marinette, Winnebago and Outagamie, and Washington and Jefferson counties.2
Where to test
- Bacteria: DNR's list of certified labs for bacteria.4
- Other contaminants: DNR's certified laboratory lists.4
- County health departments sometimes run labs. Waukesha County's lab is state-certified (see our Waukesha page).8
Free and low-cost testing and help
- County programs: contact your county health department. DHS keeps a directory of local health departments.
- Well Compensation Grant: DNR grants help eligible landowners or renters replace, reconstruct or treat a contaminated private water supply. Family income can't exceed $65,000, the program pays 75% of eligible costs up to $16,000 (a maximum grant of $12,000), and the contamination has to meet DNR's criteria (for example, arsenic at or above 50 µg/L). Work done before DNR approval isn't reimbursed, and dug wells aren't eligible.6 DNR says 2025 legislation added assistance for PFAS-contaminated wells.6
Well records
- DNR well construction reports: search by location or owner.7
Who to call
- Local health departments: DHS county directory.
- University of Wisconsin–Madison Extension: extension.wisc.edu.
- DNR: 1-888-936-7463.6
Guides for Wisconsin well owners
- Buying a home with a well
- Nitrate in well water
- Arsenic in well water
- Shock chlorinating a well
- How to read your well water test results
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Dieter, C.A., and others, 2018, Estimated Use of Water in the United States County-Level Data for 2015 (ver. 2.0), U.S. Geological Survey data release. https://doi.org/10.5066/F7TB15V5 ↩↩
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Wisconsin Department of Health Services, "What's in Your Water? A Look at Private Well Water Quality in Wisconsin" (P-01830, July 2017) (PDF). https://www.dhs.wisconsin.gov/publications/p01830.pdf ↩↩↩
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Wisconsin DNR, "Buying or selling a home or property with a private well: Property transfer well inspections." https://dnr.wisconsin.gov/topic/Wells/RETransfer.html ↩↩↩↩
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Wisconsin DNR, "Test your private well water annually." https://dnr.wisconsin.gov/topic/Wells/privateWellTest.html ↩↩↩
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Wisconsin Statutes ch. 709 (§ 709.03, Real Estate Condition Report) (PDF). https://docs.legis.wisconsin.gov/statutes/statutes/709.pdf ↩
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Wisconsin DNR, "Well Compensation Grant Program." https://dnr.wisconsin.gov/aid/WellCompensation.html ↩↩↩
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Wisconsin DNR, "Well Construction Information System" (public search). https://apps.dnr.wi.gov/wellconstructionpub/#!/PublicSearch/Index ↩
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Waukesha County, "Private Well Water Quality and Laboratory Services." https://www.waukeshacounty.gov/parks-and-land-use/environmental-health/private-well-water-quality-and-laboratory-services/ ↩