Grease Interceptor
A grease interceptor (also called a grease trap) is a plumbing device installed in the drain line of commercial kitchens to separate and capture fats, oils, and grease (FOG) before kitchen wastewater enters the municipal sewer system. Required by local plumbing codes for virtually all food service establishments, grease interceptors prevent sewer blockages and protect wastewater treatment infrastructure.
Updated July 13, 2026
Key Facts
- 1Commercial grease interceptors cost $3,000–$12,000 installed, depending on size (measured in gallons) and whether they require a concrete vault
- 2Grease interceptors must typically be pumped and cleaned every 30–90 days, with service costs ranging from $150–$400 per service call
- 3Most municipalities require grease interceptors for any food service establishment with frying, grilling, or other grease-producing cooking — and for restaurants with dishwashers
Grease Trap vs. Grease Interceptor: What's the Difference?
The terms are often used interchangeably, but they technically describe different sizes. A grease trap is a smaller, under-sink device (typically 20–50 gallon capacity) that serves one or two fixtures and must be cleaned weekly. A grease interceptor is a larger exterior unit (500–2,000+ gallon capacity) buried in the ground or in a vault outside the building, serving the entire kitchen drain system.
Most health departments and municipal utilities require a properly sized exterior grease interceptor for any commercial kitchen with significant cooking volume. Small under-sink traps are typically not accepted as a substitute for commercial food service.
Sizing and Siting a Grease Interceptor
Grease interceptors are sized based on the kitchen's drainage flow rate, the volume of grease-producing equipment, and local code requirements. The Uniform Plumbing Code and local health department rules govern sizing calculations. An undersized interceptor fills too quickly, causes backups, and results in FOG passing into the sewer.
Location matters: interceptors must be accessible for pump-out service, which requires a manhole or access cover at grade. Interior locations in tight urban sites often require a grease interceptor with an internal access point built into the floor — more expensive but compliant.
Frequently Asked Questions
Is a grease interceptor required for a coffee shop?
It depends on the menu. A coffee shop with only espresso, batch brew, and pre-packaged pastries likely does not need a grease interceptor. A café that does on-site cooking with butter, oils, or fryers typically does. Confirm with the local health department and plumbing authority during your pre-application meeting.
Who is responsible for grease interceptor maintenance?
The tenant is responsible for maintaining, cleaning, and documenting grease interceptor service — even if the interceptor was installed by the landlord. Most municipalities require maintenance logs available for inspection. Failure to maintain can result in fines and health department action.
How much does it cost to add a grease interceptor to an existing space?
Retrofitting a grease interceptor into an existing kitchen typically costs $4,000–$15,000, depending on how accessible the drain lines are and whether exterior excavation is required. Spaces with basement or crawl space access are less expensive; slab-on-grade construction requiring saw-cutting of concrete is at the high end.