Grease Trap vs. Grease Interceptor: What's the Difference?

Grease trap and grease interceptor are often used interchangeably, but they're different sizes of the same idea. A trap is the small indoor unit rated in pounds; an interceptor is the large outdoor tank rated in gallons. Here's the practical difference for your restaurant.

Grease trap vs. grease interceptor: what's the difference?

Both work on the same principle: wastewater slows down inside the device, grease cools and floats to the top, solids sink to the bottom, and cleaner water passes through to the sewer. The difference is capacity and where the unit lives.

The grease trap (smaller, indoor)

A grease trap is typically a compact unit installed inside the kitchen — under a three-compartment sink or recessed in the floor — and rated by flow and pounds of grease capacity. Because it's small, it fills quickly and needs frequent cleaning, often monthly or more for an active fryer line.

The grease interceptor (larger, outdoor)

A grease interceptor is a much larger tank, usually buried outside the building and rated in gallons (commonly 500–2,000+). Its size means it's cleaned less frequently, but a full pump-out is a bigger job. High-volume kitchens are often required by code to use an interceptor rather than an indoor trap.

Which one do you have — and which do you need?

Your local plumbing code and FOG program determine what's required, usually based on your kitchen's volume and fixtures. Whichever you have, the maintenance logic is the same: keep it below 25% capacity and document the cleaning. GreaseGiant services both — see grease trap cleaning, and if you're not sure what you've got, we'll tell you when we visit.

Frequently asked questions