If your tenant improvement includes a commercial kitchen, the grease interceptor deserves attention in the first design meeting. It is sized by code from your fixture and equipment schedule, it usually needs its own permit and sanitation-district approval, and the larger units are long-lead. On plenty of restaurant build-outs, the interceptor — not the crew — is what sets the plumbing schedule.
How it gets sized
Interceptor sizing is driven by the drainage fixture units connected to it — three-compartment sinks, pre-rinse stations, mop sinks, floor drains and dishwashers — and by the local authority’s method (fixture-based or flow-based). Get the kitchen equipment schedule locked early; a late addition of one more sink can push you to the next interceptor size.
Where it goes
- Interior hydromechanical unit — under a sink or recessed in the floor. Fast to install, needs maintenance access and a sane path for pump-out.
- Exterior in-ground gravity interceptor — a concrete vault outside. Needs site work, a truck-accessible location, and coordination with the landlord and civil drawings.
The exterior option is common for full-service kitchens and is where schedule risk concentrates: excavation, the vault lead time, and a separate inspection.
The permit path
Beyond the building plumbing permit, most jurisdictions route grease-interceptor plans through the sanitation district or a pretreatment program for a separate review and sign-off. That review runs on its own clock. We submit it in parallel with the building permit so the two approvals land together rather than in sequence.
Decide the interceptor type, size and location before the kitchen layout is final, and it stops being the thing that holds up your opening.