Fats, oils, and grease are the number one enemy of restaurant sewer lines. Here is how grease traps work, how to maintain them, and the warning signs your system is in trouble.
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An interior grease trap catches fats and oils before they reach your restaurant's sewer line.
Last updated: October 13, 2026
A grease trap is a plumbing device that catches fats, oils, and grease, collectively called FOG, before they enter the sewer line. Wastewater flows in, slows down, and the grease floats to the top while solids sink to the bottom. Only the cleaner water in the middle layer passes through to the sewer. Without one, every dish washed and every fryer cleaned sends grease straight into the pipes.
Most Ohio municipalities require food service businesses to have a grease trap or interceptor as part of their sewer pretreatment rules. This is not bureaucratic decoration: grease is the leading cause of sewer blockages in commercial districts. A restaurant without a working grease trap is one bad week away from a kitchen backup, and many cities back the requirement with inspections and fines.
Grease leaves the kitchen as a hot liquid and hardens as it cools in the pipe. The U.S. EPA tracks fats, oils, and grease as a leading cause of sewer blockages. Day after day, grease coats the pipe walls, and each layer narrows the opening a little more. Food particles and debris stick to the tacky surface, building the blockage faster. Eventually the line chokes completely, and the kitchen floor drains back up, usually at the worst possible moment.
The damage goes beyond clogs. Thick grease deposits trap moisture and acids against the pipe wall, accelerating corrosion in older metal lines. In lines that have been jetted repeatedly for grease, the pipe itself can be weakened over time. What starts as a maintenance issue becomes a structural one, and the fix jumps from cleaning to repair or replacement. A properly sized, properly maintained trap breaks this cycle at the source.
This is what unprotected lines look like inside: layer after layer of cooled grease shrinking the pipe.
Restaurants use one of two setups, depending on size and local rules:
Which one you need depends on your kitchen's output and your municipality's requirements. Undersized traps are a chronic problem: they fill between pumpings, and grease flows straight past a full trap into the line. An exterior interceptor is a buried tank, so installation means excavation: call 811 before any digging starts. If your line clogs again within weeks of a cleaning, the trap may be too small for the kitchen it serves.
Pump on the 25 percent rule, clean the whole unit, train the staff, jet the downstream line, and inspect the line annually. Maintenance is simple but non-negotiable:
Here is the maintenance schedule in one place:
| Maintenance task | How often |
|---|---|
| Pump an interior grease trap | Every 1 to 3 months, when grease and solids reach 25% of capacity |
| Pump an exterior grease interceptor | Every 3 to 6 months, when grease and solids reach 25% of capacity |
| Hydro jet the downstream line | Periodically, to clear grease the trap misses |
| Camera-inspect the line downstream of the trap | Once a year |
Exterior interceptors hold hundreds of gallons and need scheduled pumping by a professional crew.
Watch for these red flags in the kitchen:
A backup that comes back within weeks of jetting almost always points to the trap: it is full, undersized, damaged, or being bypassed. Grease trap cleaning and installation service can size, install, or replace a unit that is no longer protecting your line.
Speak in general terms, because every city writes its own rules: most Ohio municipalities with sewer pretreatment programs require food service establishments to install grease traps or interceptors, pump them on a minimum schedule, and keep records. Ohio EPA administers the statewide pretreatment framework these local programs follow. Inspectors can check the trap, review your pumping logs, and fine you for violations. Some cities set minimum trap sizes based on kitchen fixtures or seating capacity.
The financial logic is simple. Regular pumping work a fraction of a single emergency backup, and it is far simpler than a fine plus a cleanup. A grease blockage that reaches the city main can also leave your business responsible for the city's repair work. If you are opening a new restaurant, buying an existing one, or remodeling a kitchen in Columbus, Cincinnati, or Cleveland, confirm the local requirements with the water or sewer authority before you sign anything.
For a full maintenance plan that covers the trap, the lines, and everything downstream, see our commercial sewer services. And if grease has already caused a backup, emergency sewer backup service gets the kitchen back in operation fast.
Almost certainly. Most Ohio municipalities require food service establishments, restaurants, cafes, bakeries, and commercial kitchens, to install and maintain a grease trap or interceptor as part of their sewer pretreatment rules. The exact size and pumping requirements vary by city. Check with your local water or sewer authority before opening, remodeling, or buying an existing restaurant.
The common industry rule is the 25 percent rule: pump when combined grease and solids reach 25 percent of the trap's capacity. For a busy kitchen, that usually means every 1 to 3 months for interior traps and every 3 to 6 months for large exterior interceptors. Your municipality may set its own minimum schedule, so follow whichever is stricter.
It cools, solidifies, and coats the inside of the pipe, shrinking the opening a little more every day. Eventually the line blocks completely, causing a backup in the kitchen, often during a busy service. Repeated grease blockages can also damage the pipe itself, turning a cleaning problem into a repair or replacement project.
Kitchen drains that empty slowly, gurgling from floor drains, foul odors near sinks or the trap, grease visibly passing through to the outlet side, and backups that return soon after a cleaning. If hydro jetting clears the line but it clogs again within weeks, the trap is likely undersized, full, or bypassed.
Yes. Ohio municipalities with pretreatment programs can fine food service businesses for missing, undersized, or poorly maintained grease traps, and for discharging excessive grease into the public sewer. A blockage in the city main traced back to your kitchen can also leave you responsible for the cleanup work. The fines and the repair bill both exceed the work of regular pumping.
We'll inspect your trap, camera your lines, and set up a pumping schedule that keeps the kitchen running, anywhere in Ohio.
Call (614) 350-5706