Illinois county well guide

Well Water in Marion County, IL: Testing, Contractors and Rules

About 441 households in Marion County, 3% of the county, rely on a private well. Nobody tests that water unless the owner does.

Labs within 40 milesLicensed contractors
3%of households on a private well
Share on wells, county vs state
Marion County3%
Illinois average9%
1licensed contractors serve the county
<1 mito the nearest certified lab, Precision Water Lab
Nostatewide test required when a home is sold

Most of Marion County is on public water, but an estimated 441 households still rely on a private well. This page covers the rules, labs and licensed contractors that serve them.

Local rules for wells in Marion County

Private wells in Marion County follow Illinois's statewide rules, administered by Illinois Department of Public Health, Private Water Program. A water test is required when a new well is completed. There is no statewide test requirement when a home is sold, though lenders often ask for one. The cards below show the details and the official sources.

At a glance

Water test for a new wellRequired

A permit from the county health department (or IDPH where the county has no delegated program) is required before a private well is drilled, the well must be built by an IDPH licensed water well contractor to the Illinois Water Well Construction Code (steel or approved plastic casing, grout, the setbacks from septic systems and other sources, a sanitary well cap above grade), and the contractor files a well construction report with IDPH. Under the code the new well is disinfected and a bacteria sample is collected, in most counties by the health department at the final inspection, before the well is approved for use; the health department's sign-off is what the building department wants before occupancy.

Water test when a home is soldNot required statewide

No statewide requirement. The Illinois Residential Real Property Disclosure Report asks the seller about the water supply and any known defects, and FHA, VA and USDA loans require a bacteria, nitrate and lead sample from a certified lab before closing. A few counties run point-of-sale well and septic inspection programs under local ordinance, so ask the county health department.

What the state recommends

IDPH recommends testing a private well every year for coliform bacteria and nitrate, after any repair or flooding, and whenever the taste, color or smell changes; a chemistry panel (arsenic, iron, manganese, hardness, chloride, sulfate) when the well is new or every few years; and, depending on the aquifer, radium and barium for deep sandstone wells in northern Illinois, arsenic for wells in the Mahomet and other glacial aquifers of central Illinois, and pesticides and nitrate for shallow wells in farm country. County health department labs run the bacteria test cheaply, and the IDPH state lab tests samples submitted through the county.

Free or low-cost testingAvailable

No statewide free program. Most county health departments sell a bacteria (and often nitrate) sample kit for a small fee and explain the result, and the IDPH Division of Laboratories runs the bacteria test for counties without their own lab. The Illinois State Water Survey and university extension programs run periodic free nitrate and arsenic screening clinics in farm counties.

Getting your water tested near Marion County

2 certified labs within 40 miles serve Marion County, starting with Precision Water Lab in Centralia (in the county). Each card below shows whether the lab takes homeowner samples and which tests it is certified for.

2 certified labs within 40 miles

Licensed well contractors serving Marion County

1 licensed contractor serve Marion County, including Stephen Gerald Sutter. 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

Wells in Marion County typically reach 30 to 250 ft, varying with the geology more than in most states: shallow sand and gravel wells of 30 to 120 ft in the river valleys and central Illinois (Sangamon and Madison county medians are under 60 ft), 90 to 250 ft in the glacial drift of the Chicago collar counties (McHenry 70 to 200 ft, Lake 90 to 230 ft), and 200 to 660 ft for the dolomite and sandstone bedrock wells of Kane, Cook, Will, Jo Daviess and the northern tier; southern Illinois bedrock wells are 150 to 350 ft and low-yielding. What comes up with the water depends on the aquifer, and across Illinois the usual suspects are arsenic (naturally occurring in the glacial sand and gravel aquifers of central and northeastern illinois, including the mahomet aquifer, where roughly one well in ten is over the standard), iron and manganese (nearly universal in glacial aquifers). 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
  • Arsenic (naturally occurring in the glacial sand and gravel aquifers of central and northeastern Illinois
  • Including the Mahomet aquifer
  • Where roughly one well in ten is over the standard)
  • Iron and manganese (nearly universal in glacial aquifers)
  • Hardness (very hard water statewide)
  • Radium and barium (the deep Cambrian-Ordovician sandstone aquifer of northern Illinois)
  • Coliform bacteria (old large-diameter bored and dug wells
  • Common in southern Illinois)
  • Nitrate and atrazine (shallow wells in corn and soybean country)
  • Chloride and sodium (road salt in the Chicago collar counties
  • And natural brine in deep wells)
  • Hydrogen sulfide and methane (deep wells in the south and the coal counties)
  • Fluoride (locally high in deep aquifers)

Neighboring counties: Jefferson County, Clinton County, Washington County, Fayette County.

What well work costs in Marion County

Bacteria test (coliform and E. coli)$30published Illinois lab fees
Nitrate testIncludedpart of the bacteria test above
Broad panel (metals and minerals)$85 to $450state and university lab packages
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

County health department lab: one $30 test covers coliform, E. coli and nitrate (McHenry County). Installed costs are national 2026 ranges; local quotes vary with depth, access and materials. Sources, checked September 2026: McHenry County Health Department lab, HomeGuide cost guides, Angi: cost to shock a well.

Questions Marion County well owners ask

How many homes in Marion County are on a well?

About 441, or 3% 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 Marion County?

Precision Water Lab in Centralia, inside the county. It accepts homeowner samples.

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

A permit from the county health department (or IDPH where the county has no delegated program) is required before a private well is drilled, the well must be built by an IDPH licensed water well contractor to the Illinois Water Well Construction Code (steel or approved plastic casing, grout, the setbacks from septic systems and other sources, a sanitary well cap above grade), and the contractor files a well construction report with IDPH. Under the code the new well is disinfected and a bacteria sample is collected, in most counties by the health department at the final inspection, before the well is approved for use; the health department's sign-off is what the building department wants before occupancy.

What does a well test cost near Marion County?

Published lab fees in Illinois: $30 for a bacteria test that also covers nitrate. County health department lab: one $30 test covers coliform, E. coli and nitrate (McHenry County). Mail-in kits cost about the same as walking in.