What to test for, and how often
- Coliform bacteria, every year. Coliform indicates surface contamination has reached the well. If found, Illinois EPA says to boil water for drinking and cooking and to disinfect the well.
- Nitrate, every year, and always before giving the water to an infant. Water above 10 mg/L nitrate as nitrogen should not be given to infants. Do not boil water to treat nitrate; boiling concentrates it.
- Other tests: radium occurs naturally in some northern Illinois groundwater. Ask the health department which extra tests fit your well.
Getting a kit in Kankakee County
The Kankakee County Health Department's well program provides sample kits for nitrate and coliform at 2390 W Station St, Kankakee. Kits can be picked up Monday through Friday, 8:30 a.m. to 4:30 p.m. Samples are accepted Monday, Tuesday and Wednesday, and must be returned the same day they are taken, by 3:00 p.m. Fees are on the department's fee schedule; our research in October 2026 found $50 per test.
Why it matters here
USGS estimated that about 23.5% of Kankakee County residents (26,679 people) supplied their own household water from groundwater in 2010. A state geological study found aquifers in the Kankakee area within about 5 to 20 feet of the surface with high-to-moderate contamination potential, and Illinois EPA notes nitrate is a common contaminant in Illinois groundwater, often from septic systems, manure storage, feedlots, or farm fields near a well.
After pump or well work
Opening a well can introduce bacteria. Ask the contractor whether they will disinfect the well, and test for coliform afterward.
When to call a contractor instead
Testing is done through the health department or a certified lab, not through us. If results point to a problem with the well itself, such as a damaged casing or a pump drawing sediment, or you want treatment equipment installed, we can refer you to an independent well contractor. For a rotten-egg smell or a sudden pump problem, see no water from your well.
Sources
Checked October 2026. We link the public source for every figure on this page.
- Illinois EPA, Well Water Testing — yearly bacteria and nitrate testing
- Kankakee County Health Department, Well Program — water sample kits, sample days, permits
- USGS, Estimated Use of Water in the United States, county data 2010 (Kankakee County, FIPS 17091: self-supplied domestic population 26,679 of 113,449) — share of residents on self-supplied (well) water