Wisconsin county well guide

Well Water in St. Croix County, WI: Testing, Contractors and Rules

About 17,225 households in St. Croix County, 49% of the county, rely on a private well. Nobody tests that water unless the owner does.

Labs within 40 milesLicensed contractors
49%of households on a private well
Share on wells, county vs state
St. Croix County49%
Wisconsin average28%
41licensed contractors serve the county
9 mito the nearest certified lab, Quality Water Testing, Inc.
Nostatewide test required when a home is sold

Most homes in St. Croix County are on a private well: about 17,225 households, 49% of the county. That makes St. Croix County one of the places in Wisconsin where the water department is the homeowner.

Local rules for wells in St. Croix County

Wisconsin’s well code (NR 812) applies in St. Croix 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 St. Croix County

12 certified labs within 40 miles serve St. Croix County, starting with Alliance Technical Group, LLC DBA Interpoll Laboratories in Circle Pines (about 30 miles from the county center). Each card below shows whether the lab takes homeowner samples and which tests it is certified for.

3 certified labs within 40 miles

Licensed well contractors serving St. Croix County

33 licensed contractors serve St. Croix County, including A Well Pump Guy LLC and A.c.e. Soil & Site Evaluations 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: Pierce County, Polk County, Dunn County, Pepin County.

What well work costs in St. Croix County

Bacteria test (coliform and E. coli)$28 to $35published Wisconsin lab fees
Nitrate test$35 to $41published Wisconsin lab fees
Broad panel (metals and minerals)$450published Wisconsin lab fees
Well inspection$250 to $550$350 to $900 with water testing
Submersible pump replacement$1,000 to $2,500installed; deep wells cost more
Pressure tank replacement$800 to $1,500installed
One treatment unit$700 to $3,500softener, iron filter or UV, installed
Multi-stage whole-house treatment$2,500 to $10,000+several units or whole-house RO, installed
New well, complete$6,000 to $16,000typical 200 ft well with pump; drilling alone about $20 to $30 per foot; deeper wells cost more
Shock chlorination$80 to $200by a contractor; under $30 to do yourself

Wisconsin State Laboratory of Hygiene ($35 each, $450 homeowner package) and county labs (Marathon County: $28 bacteria, $41 nitrate, $61 for both). Free through WellTAP for eligible households. Installed costs are national 2026 ranges; local quotes vary with depth, access and materials. Sources, checked September 2026: Wisconsin State Laboratory of Hygiene prices, Marathon County water testing, HomeGuide cost guides, Angi: cost to shock a well.

Questions St. Croix County well owners ask

How many homes in St. Croix County are on a well?

About 17,225, or 49% 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 St. Croix County?

Alliance Technical Group, LLC DBA Interpoll Laboratories in Circle Pines, about 30 miles away. It accepts homeowner samples.

Do I need a permit to drill a well in St. Croix 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 St. Croix 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.