Wisconsin county well guide

Well Water in Green Lake County, WI: Testing, Contractors and Rules

About 3,804 households in Green Lake County, 50% of the county, rely on a private well. Nobody tests that water unless the owner does.

Labs within 40 milesLicensed contractors
50%of households on a private well
Share on wells, county vs state
Green Lake County50%
Wisconsin average28%
23licensed contractors serve the county
12 mito the nearest certified lab, U.S. Water, LLC
Nostatewide test required when a home is sold

Most homes in Green Lake County are on a private well: about 3,804 households, 50% of the county. That makes Green Lake County one of the places in Wisconsin where the water department is the homeowner.

Local rules for wells in Green Lake County

Wisconsin’s well code (NR 812) applies in Green Lake 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 Green Lake County

14 certified labs within 40 miles serve Green Lake County, starting with Agsource Laboratories in Marshfield (about 12 miles from the county center). Each card below shows whether the lab takes homeowner samples and which tests it is certified for.

15 certified labs within 40 miles

Davy Laboratories

WI certified

La Crosse, WI · Commercial12 mi

Homeowner samples · Mail-in kits

  • Arsenic
  • Coliform Bacteria
  • Full Homeowner Panel
  • Hardness
  • Iron and Manganese
  • Lead
  • Nitrate / Nitrite
  • Volatile Organic Compounds

Licensed well contractors serving Green Lake County

22 licensed contractors serve Green Lake County, including Al’s Plumbing LLC and Anthony W Thoma. 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: Waushara County, Marquette County, Fond du Lac County, Winnebago County.

What well work costs in Green Lake 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 Green Lake County well owners ask

How many homes in Green Lake County are on a well?

About 3,804, or 50% 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 Green Lake County?

Agsource Laboratories in Marshfield, about 12 miles away. It accepts homeowner samples.

Do I need a permit to drill a well in Green Lake 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 Green Lake 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.