Illinois Grease Trap Regulations
FOG Compliance Overview
Illinois follows the International Plumbing Code (IPC) as its base plumbing code. The IPC requires grease interceptors for food service establishments and references sizing based on fixture unit counts and flow rates. The state's regulatory authority is the Illinois Environmental Protection Agency (IEPA).
With approximately 28,496 food service establishments statewide, Illinois has significant FOG compliance needs. Individual cities and municipalities may adopt additional local ordinances that go beyond the state plumbing code, including stricter pumping schedules, permit requirements, and enforcement penalties. Of the 6 cities we cover, 4 require a dedicated FOG permit. 4 cities enforce the 25% rule for grease trap pumping.
Need a grease trap in Illinois?
Our free calculator uses IPC code requirements to recommend the right size for your establishment.
Size My Grease TrapCity Regulations in Illinois
| City | Pumping Frequency | Permit | 25% Rule |
|---|---|---|---|
| Aurora | Quarterly (every 90 days) or as often as necessary to e... | Required | Yes |
| Chicago | Every 90 days minimum or when 25% full (whichever comes... | Required | Yes |
| Glen Ellyn | Quarterly | — | — |
| Joliet | Monthly minimum by licensed grease hauler (unless diffe... | Required | Yes |
| Naperville | Regular cleaning per manufacturer specifications and ci... | Required | Yes |
| Peoria | See details | — | — |
Frequently Asked Questions
What plumbing code does Illinois follow for grease traps?
Illinois follows the International Plumbing Code (IPC). The IPC requires grease interceptors for food service establishments and sizes them based on fixture unit counts and flow rates. Individual cities may adopt stricter local ordinances.
How many food service establishments are in Illinois?
Illinois has approximately 28,496 food service establishments according to Census Bureau County Business Patterns data. We currently cover detailed FOG regulations for 6 cities in the state.
Do I need a grease trap permit in Illinois?
Permit requirements vary by city. Of the 6 cities we cover in Illinois, 4 require a dedicated FOG permit. Check your specific city's requirements below or contact your local wastewater authority.
What size grease trap do I need in Illinois?
Grease trap sizing in Illinois depends on your establishment's flow rate, number of fixtures, and local code requirements under the IPC. Use our free sizing calculator for a recommendation tailored to your setup.
Regulations change frequently. Always verify current requirements with your local wastewater authority or plumbing inspector before making compliance decisions. Last updated: March 2026.