Illinois county well guide

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

About 1,990 households in Warren County, 28% of the county, rely on a private well. Nobody tests that water unless the owner does.

Labs within 40 milesLicensed contractors
28%of households on a private well
Share on wells, county vs state
Warren County28%
Illinois average9%
4licensed contractors serve the county
40+ mito a certified lab; mail-in kits recommended
Nostatewide test required when a home is sold

About one in 4 households in Warren County relies on a private well, around 1,990 homes. Outside the towns with public water, wells are the norm here.

Local rules for wells in Warren County

The rules that apply in Warren County are set at the state level in Illinois. New wells must be tested before use, and nothing is required at sale. Some counties and townships add permits or setbacks of their own, so check locally before drilling. The state's own recommendations are below.

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 Warren County

Warren County has no certified lab within 40 miles, so most owners here test by mail. Order bottles from a certified lab, sample from the cold tap before any treatment, and ship the same day with an ice pack.

No listings yet for this area. Try widening your search.

Licensed well contractors serving Warren County

Licensed help in Warren County includes Chase Andrew Flatt and Joseph W Allen, Corwin D Gingerich and Klint D Gingerich and 2 others. Every listing was matched to the Illinois license list; the "verify" link on each profile opens the state lookup.

Well depth and water chemistry

Well depth and water chemistry in Warren County follow the rock underneath it. Typical wells here run 140 to 240 feet; the median of 246 private water wells on the ISGS ILWATER map drilled since 2000 is 200 feet. Contaminants worth testing for in this part of Illinois include 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).

Typical well depth

140 to 240 feet; the median of 246 private water wells on the ISGS ILWATER map drilled since 2000 is 200 feet

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: Knox County, Henderson County, Mercer County, McDonough County.

What well work costs in Warren 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 Warren County well owners ask

How many homes in Warren County are on a well?

About 1,990, or 28% 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 Warren County?

There is no certified lab within 40 miles. Use a mail-in kit from a Illinois certified lab, or the county health department if it collects samples.

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

A bacteria and nitrate test runs $25 to $75 at most certified labs; a full panel with metals is $150 to $400. Mail-in kits cost about the same as walking in.