Wisconsin county well guide

Well Water in Jefferson County, WI: Testing, Contractors and Rules

About 11,664 households in Jefferson County, 35% of the county, rely on a private well. Nobody tests that water unless the owner does.

Labs within 40 milesLicensed contractors
35%of households on a private well
Share on wells, county vs state
Jefferson County35%
Wisconsin average28%
56licensed contractors serve the county
11 mito the nearest certified lab, Watertown Department of Public Health
Nostatewide test required when a home is sold

Jefferson County has an estimated 11,664 households on private wells, 35% of the county. If you are one of them, testing, treatment and repairs are yours to arrange.

Local rules for wells in Jefferson County

Wisconsin’s well code (NR 812) applies in Jefferson County: a licensed well driller files a notification with the DNR before drilling, and the driller must sample the new well for bacteria and nitrate before it goes into service. There is no required test at sale, but any paid well inspection for a real-estate deal must be done by a licensed driller or pump installer and must include bacteria, nitrate and arsenic.

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.

Getting your water tested near Jefferson County

9 certified labs within 40 miles serve Jefferson County, starting with Watertown Department of Public Health in Watertown (about 11 miles from the county center). Each card below shows whether the lab takes homeowner samples and which tests it is certified for.

9 certified labs within 40 miles

Licensed well contractors serving Jefferson County

54 licensed contractors serve Jefferson County, including 4-D Water Well & Pump Service LLC and Absolute Pump & Well Service LLC. Each profile carries the state license number and the date we checked it, and the filters below sort them by drilling, pump work or treatment.

Well depth and water chemistry

What comes up with the water depends on the aquifer. A first full panel tells you which of them apply to your well.

Typical well depth

Varies by location. Check the state well record search for logs of nearby wells.

Contaminants to test for
  • Coliform bacteria
  • Nitrate
  • Arsenic (Fox River Valley
  • St. Peter sandstone)
  • Manganese
  • Iron
  • Hardness
  • Strontium (eastern counties)
  • Radium (eastern deep sandstone aquifer)
  • PFAS (Marinette
  • Peshtigo
  • Dane County areas)
  • Lead

Neighboring counties: Dodge County, Walworth County, Waukesha County, Rock County.

What well work costs in Jefferson County

Basic bacteria and nitrate test$25 to $75lab fee, homeowner sample
Full panel lab test$150 to $400metals, VOCs, radiologicals
Well inspection$250 to $550flow, pressure, visual, water test
Submersible pump replacement$1,200 to $4,500parts and labor
Pressure tank replacement$400 to $1,200installed
Whole-house treatment system$800 to $6,000softener, iron filter, UV, RO
New well drilled$5,500 to $25,000about $25 to $65 per foot
Shock chlorination$80 to $300or about $20 as a DIY job

National ranges from published 2025 to 2026 contractor pricing. Local quotes vary with depth, access and materials.

Questions Jefferson County well owners ask

How many homes in Jefferson County are on a well?

About 11,664, or 35% of households, based on Census housing data and state well surveys. The share is highest outside the towns with public water.

Where is the closest certified lab to Jefferson County?

Watertown Department of Public Health in Watertown, about 11 miles away. It accepts homeowner samples.

Do I need a permit to drill a well in Jefferson County?

A well notification and fee must be filed with the Wisconsin DNR before drilling, and only a DNR-licensed well driller may drill it. Some counties add their own permit or setback review, so check with the county land conservation or zoning office.

What does a well test cost near Jefferson County?

A bacteria and nitrate test runs $25 to $75 at most certified labs; a full panel with metals is $150 to $400. Several county health departments and the state lab of hygiene sell homeowner kits for bacteria and nitrate at low cost; ask the county about screening clinics.