Illinois: Certified labs by state

Illinois splits private-well oversight across agencies: Illinois EPA handles community drinking-water issues and chemical lab accreditation, while IDPH oversees private-water-well permits, inspections, and microbiological support; local health departments are heavily involved. Illinois official pages also flag naturally occurring contaminants such as arsenic, radon, and radium, plus nitrate concerns tied to agriculture and septic systems. ([epa.illinois.gov](https://epa.illinois.gov/topics/drinking-water/private-well-users.html))

Checked against official sources on October 4, 2026. Rules and links change; confirm with the office listed before you act.

Official resources in Illinois

Illinois EPA Accredited Labs

Official Illinois lab-accreditation page linking to the current accredited-laboratory list for chemical and microbiological drinking-water testing.

Illinois EPA Private Well Users

State hub for private-well owners with Illinois-specific guidance on testing, contaminants, maintenance, and groundwater notices.

IDPH Well Sampling for Coliform & Nitrate

IDPH fact sheet explaining how to sample a private well and the state’s baseline recommendation for coliform and nitrate testing.

IDPH Division of Environmental Health / Environmental Engineering Section

Program overview showing IDPH’s role in private water wells, permits, inspections, contractor licensing, and local health department assistance.

PrivateWellClass.org

Free Illinois-led educational program from the Illinois State Water Survey and RCAP with well-owner training, webinars, and seasonal testing campaigns.

Key facts for Illinois

IL ELAP accredits chemical analyses; IDPH accredits microbiological analyses for Illinois drinking-water labs. ([epa.illinois.gov](https://epa.illinois.gov/topics/labs/lab-accreditation/accredited-labs.html))
IDPH recommends annual private-well testing, and new or repaired wells should also be tested. ([dph.illinois.gov](https://dph.illinois.gov/topics-services/environmental-health-protection/private-water/fact-sheets/well-sampling-coliform-nitrate.html))
Nitrate is a common Illinois groundwater contaminant, often linked to septic systems, manure, feedlots, or fertilizer. ([dph.illinois.gov](https://dph.illinois.gov/topics-services/environmental-health-protection/private-water/fact-sheets/well-sampling-coliform-nitrate.html))
Illinois EPA says private-well groundwater can be affected by natural pollutants including arsenic and radon. ([epa.illinois.gov](https://epa.illinois.gov/topics/drinking-water/private-well-users.html))
IDPH says high radium levels occur primarily in the northern third of Illinois. ([idph.illinois.gov](https://idph.illinois.gov/envhealth/factsheets/radium.htm))
IDPH says central and northern Illinois have higher radon levels in soil. ([idph.state.il.us](https://www.idph.state.il.us/envhealth/factsheets/radon.htm?utm_source=openai))

What to do next

Use the Illinois EPA accredited-labs page first; choose a lab with the needed analytes, since some contaminants require chemical accreditation and bacteria requires microbiological accreditation. ([epa.illinois.gov](https://epa.illinois.gov/topics/labs/lab-accreditation/accredited-labs.html))
At minimum, test yearly for coliform and nitrate/nitrite; add VOCs if you are near businesses, industry, gas stations, or leaking fuel tanks, and ask your local health department about metals or PFAS. ([dph.illinois.gov](https://dph.illinois.gov/topics-services/environmental-health-protection/private-water/fact-sheets/well-sampling-coliform-nitrate.html))
Keep a well file with the well log, service records, and past test results, and inspect the wellhead yearly for cap damage, cracks, or debris. ([dph.illinois.gov](https://dph.illinois.gov/resource-center/news/2024/april/2024-04-30---idhp-state-water-survey-remind-private-well-owners.html))

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