Grease Trap Regulations in Illinois

Overview

Illinois food service operators must follow FOG pretreatment rules. The Illinois Environmental Protection Agency (IEPA) and local sewer utilities enforce them. Plumbing systems for commercial kitchens that waste grease, fats, or culinary oils must include grease interceptors. The Metropolitan Water Reclamation District of Greater Chicago (MWRDGC) was set up in 1889. It is the wastewater treatment and stormwater agency for the City of Chicago and 128 suburban communities across Cook County. It plays a primary role in FOG enforcement. State law requires grease trap sludge generators, haulers, and management facility operators to keep shipping papers for at least 2 years. They must produce them on request from the IEPA or treatment works owners.

Governing Authorities

The Illinois EPA runs the state's construction and operating permit program under the state Environmental Protection Act. Rules come from the Illinois Pollution Control Board. Permits are required to build new sewage treatment plants, pretreatment equipment, and industrial wastewater treatment plants. Permits are also required to expand or modify those systems. The Illinois Plumbing Code sets baseline grease interceptor rules for institutions and commercial kitchens statewide.

The Metropolitan Water Reclamation District of Greater Chicago is a special-purpose district. It has operated in Cook County since 1889. It is the wastewater treatment and stormwater agency for the City of Chicago and 128 suburban communities. The MWRD runs seven service areas. Each area sends its wastewater to a different treatment plant through the sewer system. Plant capacity ranges from 1.4 billion gallons per day at the Stickney Water Reclamation Plant down to 2.3 million gallons per day at the Lemont Plant. Beyond MWRDGC, downstate utilities also enforce rules. Fox Metro Water Reclamation District in Aurora and local city sewer authorities enforce interceptor rules, pumping schedules, and manifest retention.

Key Requirements

Plumbing systems for institutions or commercial kitchens that waste grease, fats, culinary oils, or similar food prep waste must include grease interceptors. All waste lines and drains carrying grease, fats, or culinary oil in those kitchens must run to one or more interceptors.

Interceptor Sizing and Installation

• A grease interceptor installed on the same floor as the fixture must have one-half the liquid-holding capacity of the fixture. A grease interceptor on a floor below the fixture must have 60 percent of the liquid-holding capacity of the fixture.
• Grease interceptors must be built of durable, corrosion-resistant materials. They must have water-tight covers fastened in place.
• No grease interceptor may receive the discharge from a food waste disposal.
• All interceptors must be installed in a spot where the lid and contents can be removed easily.
• Water-cooled grease interceptors are banned.

Cleaning Frequency

• Chicago rules usually require grease traps to be cleaned at least once every 90 days. Actual frequency depends on kitchen size, volume, and the type of food prepared. High-volume restaurants and those serving mostly fried foods may need monthly cleaning.
• The industry standard "25% rule" calls for cleaning when FOG and solids reach 25% of the trap's capacity.
• Some cities require clean out and removal at least monthly. Local authorities may set a less or more frequent schedule.

Record-Keeping and Manifests

• Owners must keep detailed upkeep logs of all cleaning dates, service provider info, and waste disposal records for at least three years.
• Each shipping paper must contain, at a minimum: the name and phone number of the sludge generator, the street address of the grease trap, the volume of grease trap sludge removed, the legible signature of a representative of the generator, and the date of removal. It must also include the name, address, and phone number of the sludge transporter.
• The sludge generator, transporter, and management facility operator each must keep a copy of the shipping paper for at least 2 years. They must produce it on request from the IEPA or the owner of the treatment works.
• No person may discharge, deposit, or dispose of grease trap sludge into a treatment works or any sewer running to a treatment works. The only exception is express authorization, by ordinance or license, from the owner of the treatment works and the owner of the sewer.

Fines and Enforcement

Chicago enforces grease trap rules through a step-by-step penalty structure. First violations usually bring written warnings and compliance orders with set deadlines. Continued non-compliance can trigger fines starting at $500. Fines can climb to $10,000 for repeated or severe violations. Beyond money penalties, non-compliant kitchens may face limits on business operations. That includes possible suspension of food service licenses until violations are fixed.

Some cities cap fines at $750 for any one offense for grease trap violations. Violations of Illinois grease trap sludge statutes are subject to the civil penalties in subsection (a) of Section 42 of the Environmental Protection Act. If the owner of a treatment works brings or backs the action, the owner is entitled to recover 75% of any penalties.

City officials may run unannounced inspections to verify compliance with grease trap upkeep rules. In serious cases involving environmental damage from FOG discharge, kitchens may also face penalties under the federal Clean Water Act.

Major City FOG Programs

Chicago

Under Chicago's Municipal Code, all food service kitchens must install grease interceptors to capture FOG. The size and type must match the kitchen's wastewater volume. In 2026, grease trap cleaning is required by the Metropolitan Water Reclamation District to protect waterways and infrastructure. Chicago rules usually require grease traps to be cleaned at least once every 90 days. Smaller cafes may meet the rule with quarterly service. High-volume restaurants may need monthly cleaning. Owners must keep detailed records of all upkeep on their grease interceptors. That includes cleaning and pumping dates, service provider name, and FOG volume removed. Records must be kept for three years. Continued non-compliance can trigger fines starting at $500 and climbing to $10,000 for repeated or severe violations.

Aurora

Aurora is served by the Fox Metro Water Reclamation District. The district handles wastewater conveyance and treatment for Aurora and the surrounding area. The city requires commercial grease trap installation permits for food service kitchens. Grease interceptor sizing follows the Illinois Plumbing Code. All waste lines carrying FOG must run to approved interceptors. Local enforcement includes inspections and compliance monitoring by the water reclamation district.

Naperville

Naperville is Illinois' fifth-largest city, with over 140,000 residents. It sits in DuPage County and enforces grease interceptor rules for commercial food kitchens. Kitchens must follow Illinois Plumbing Code Section 890.510 for sizing and installation. Local utilities run routine inspections. They require proper manifest paperwork for all grease trap pumping. Cleaning frequency depends on kitchen size and volume. It usually runs from monthly to quarterly.

Rockford

Rockford sits in northern Illinois, with over 150,000 residents in Winnebago County. The city keeps grease interceptor rules in its municipal code and through its local sewer authority. Food service kitchens must install properly sized grease interceptors and pump them on a regular schedule. The city follows state plumbing code rules for sizing and construction. Local enforcement includes routine inspections and recordkeeping rules in line with state FOG rules.

Frequently Asked Questions

How often must I have my grease trap pumped in Illinois?

Chicago rules usually require grease traps to be cleaned at least once every 90 days. Actual frequency depends on your kitchen's size, volume, and the type of food prepared. High-volume restaurants and those serving mostly fried foods may need monthly cleaning. Smaller cafes may meet the rule with quarterly service. The industry standard "25% rule" calls for cleaning when FOG and solids reach 25% of the trap's capacity. Outside Chicago, rules vary by city. Most follow similar quarterly or monthly schedules.

What records must I keep for grease trap maintenance?

Owners must keep detailed upkeep logs of all cleaning dates, service provider info, and waste disposal records for at least three years. Each shipping paper must include the name and phone number of the sludge generator, the street address of the grease trap, the volume of grease trap sludge removed, the legible signature of a representative of the generator, and the date of removal. Generators, transporters, and management facility operators each must keep a copy of the shipping paper for at least 2 years. They must produce it on request from the IEPA or the owner of the treatment works.

Can I use enzymes or additives in my grease trap?

No. Many Illinois cities ban enzymes and emulsifiers in grease interceptors. These products do not eliminate grease. They break it down for a short time. That lets FOG re-enter the sewer system, where it can cause blockages downstream. Only physical removal of grease through pumping by a licensed hauler is allowed. Routine mechanical cleaning and pumping are the only approved ways to keep your grease trap working and stay compliant.

Find Grease Trap Service in Illinois

We list 37 licensed grease trap service providers serving Illinois communities. These certified haulers offer pumping, cleaning, and manifest paperwork to help your kitchen stay compliant with state and local FOG rules. Visit our Illinois grease trap service directory to find providers in your area, compare services, and confirm your business meets all IEPA and local utility rules for grease interceptor upkeep.