Illinois well water testing: health departments and IDPH help
Short answer: Start with your local health department, since the Illinois Department of Public Health says most can help test for bacteria and nitrate. Commercial labs also test well water and may be the only option for some contaminants. IDPH can help you choose a lab and interpret results for free.
The U.S. Geological Survey estimated that about 1.15 million people in Illinois supplied their own household water in 2015. USGS says the most common source of self-supplied water is a well. [source] [source]
When to test
IDPH says to test your well when there are known well water problems in the area, after flooding, land disturbance or nearby waste disposal, after repairing or replacing any part of the well system, and when the water's taste, color or smell changes. [source]
Where to test
- Local health department: most can help test for bacteria and nitrate. [source] [source]
- Commercial labs: may be the only option for some contaminants, and IDPH can help you select one. [source]
- Help with results: IDPH interprets results and gives recommendations for free: 217-782-5830. [source] Illinois EPA also lists the Illinois State Water Survey's Public Service Laboratory, 217-333-9234. [source]
If something is found
IDPH's advice: if bacteria are found, boil water before using it for drinking and cooking. If nitrate is found, do not boil the water, because boiling concentrates nitrate. IDPH notes that nitrate is linked to "blue baby syndrome" in infants six months old or younger. [source]
County guides
No county pages for this state yet. Your local health department is the first stop, per EPA guidance. [source]
FAQ
Where can I get my well water tested in Illinois?
Start with your local health department, since the Illinois Department of Public Health says most can help test for bacteria and nitrate. Commercial labs also test well water and may be the only option for some contaminants. IDPH can help you choose a lab and interpret results for free.
Will IDPH interpret my well test results?
Yes. IDPH says it can help interpret test results and provide recommendations for free.
Sources
- USGS – Estimated Use of Water in the United States, County-Level Data for 2015 (domestic self-supplied population) (accessed 2026-10-23)
- USGS – Domestic Water Use (accessed 2026-10-23)
- Illinois Department of Public Health – Private Well Testing (accessed 2026-10-23)
- Illinois EPA – Private Well Users: Where to Get Help (accessed 2026-10-23)
- US EPA – Protect Your Home's Water (accessed 2026-10-23)
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