Private well guide

Well Water in Wisconsin: Testing, Rules, Labs and Licensed Contractors

639,228 households in Wisconsin get their water from a private well. Here is what the state requires, where to get it tested, and who is licensed to work on it.

Find a certified labLicensed contractorsPick my county
1,067Licensed contractorschecked against state records
72Certified labsfrom the state certified list
72Counties covered
639,228Households on wells28% of households (est.)

Wisconsin has more private wells per household than almost any state, and the DNR regulates the well itself closely: who may drill it, how it is built, and what the driller must test before you use it. After that first test the water is yours to watch. Arsenic, nitrate, bacteria and manganese are the reasons to keep watching.

What comes out of the ground in Wisconsin

The Fox River Valley and the St. Peter sandstone counties have some of the highest naturally occurring arsenic in the Midwest. Nitrate follows farmland and septic density across the central sands and the southwest. Deep sandstone wells in the eastern counties can carry radium and strontium, and coliform bacteria show up in shallow wells and fractured limestone country every spring. The Marinette and Peshtigo area and parts of Dane County have PFAS in private wells. DHS recommends a bacteria and nitrate test every year, arsenic and lead at least every five years, and a one-time fluoride and manganese check.

NR 812: what the driller must do and what is on you

Before a well is drilled, the licensed driller files a well notification with the DNR and pays the fee. Once the well is finished, the driller samples it for coliform bacteria and nitrate and sends the results to you and to the DNR; the pump installer takes a bacteria sample after any new pump. Wisconsin does not require a test when a home is sold, but if a well is inspected for a sale, only a licensed driller or pump installer may do the paid inspection and it must include bacteria, nitrate and arsenic. Every well constructed since 1988 has a construction report on file, searchable by address.

At a glance

Water test for a new wellRequired

Under NR 812 the well driller must collect a bacteria (coliform) and nitrate sample from every new well and report the results to DNR; the pump installer collects a bacteria sample after installing or replacing a pump. A well notification form and fee are filed with DNR before drilling.

Water test when a home is soldNot required statewide

No statewide requirement at sale. If a well is inspected for a real-estate transaction, only a licensed well driller or pump installer may perform the paid inspection, and the inspection must include bacteria, nitrate and arsenic tests.

What the state recommends

DNR and DHS recommend testing for coliform bacteria and nitrate every year, arsenic and lead at least every 5 years (arsenic yearly in known areas of the Fox River Valley), fluoride once, and manganese, PFAS or radium where local conditions warrant. Test any time taste, color or odor changes or after flooding.

Free or low-cost testingAvailable

Some county health departments and UW Extension programs run subsidized nitrate and bacteria screening clinics; check the county health department. The DNR-certified lab list shows which labs accept homeowner samples.

Certified labs, county health departments and the State Lab of Hygiene

The DNR certifies labs for drinking water, and most county health departments either run a small bacteria and nitrate lab or sell kits from one that does. The Wisconsin State Laboratory of Hygiene sells homeowner kits by mail for bacteria, nitrate, metals and PFAS. The list below shows which labs accept homeowner samples and which tests each is certified for.

72 certified labs

See all 72 certified labs in Wisconsin

DNR-licensed well drillers and pump installers

The DNR licenses well drillers, pump installers and, separately, heat exchange drillers for geothermal loops. The profiles below come from the DNR service directories and carry the license numbers, the counties each business lists as its service area, and the date we checked the listing against the DNR directory.

1067 licensed contractors

See all 1,067 licensed contractors in Wisconsin

By county

Well depth runs from 60 feet in sand-and-gravel country to more than 500 in the eastern sandstone. Each county page carries its own numbers, the nearest labs and the contractors that serve it.

Wisconsin well water questions

Do I need a permit to drill a well in Wisconsin?

The driller files a well notification with the DNR before drilling and pays the notification fee; there is no separate homeowner permit from the state. Some counties add their own permit or setback review, so check with the county land conservation or zoning office.

Is a water test required when I sell my house?

No statewide test is required. If the buyer or lender asks for a well inspection, Wisconsin requires that a licensed driller or pump installer do it and that bacteria, nitrate and arsenic be tested.

How do I find the construction report for my well?

Search the DNR Well Construction Reports database by address, county or well ID. Reports since 1988 are online and show the depth, casing, static water level and the driller.

Where is arsenic a problem in Wisconsin?

The Fox River Valley (Outagamie, Winnebago and Brown counties) and other counties over the St. Peter sandstone have the highest rates. DHS recommends yearly arsenic testing there and at least every five years everywhere else.