Illinois county well guide

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

About 2,992 households in DeKalb County, 7% of the county, rely on a private well. Nobody tests that water unless the owner does.

Labs within 40 milesLicensed contractors
7%of households on a private well
Share on wells, county vs state
DeKalb County7%
Illinois average9%
10licensed contractors serve the county
21 mito the nearest certified lab, Suburban Laboratories (Metiri Group Geneva)
Nostatewide test required when a home is sold

About 2,992 homes in DeKalb County are on a private well. That is 7% of households, enough that every township has well owners and few of them have had the water tested recently.

Local rules for wells in DeKalb County

The rules that apply in DeKalb 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 DeKalb County

The nearest certified lab is Suburban Laboratories (Metiri Group Geneva) in Geneva, about 21 miles from the county center, and it accepts samples from homeowners. There are 8 more within 40 miles, listed below with what each tests for.

9 certified labs within 40 miles

Licensed well contractors serving DeKalb County

Licensed help in DeKalb County includes Allen E Smith, Jr and Christopher M Smith and Bradley Stone and 8 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 DeKalb County follow the rock underneath it. Typical wells here run 180 to 280 feet; the median of 485 private water wells on the ISGS ILWATER map drilled since 2000 is 240 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

180 to 280 feet; the median of 485 private water wells on the ISGS ILWATER map drilled since 2000 is 240 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: Kane County, Kendall County, Boone County, Ogle County.

What well work costs in DeKalb 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 DeKalb County well owners ask

How many homes in DeKalb County are on a well?

About 2,992, or 7% 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 DeKalb County?

Suburban Laboratories (Metiri Group Geneva) in Geneva, about 21 miles away. It accepts homeowner samples.

Do I need a permit to drill a well in DeKalb 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 DeKalb 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.