Grease Trap

A grease trap is a passive separation device installed in the drain line, usually near the kitchen or dishwashing area, that slows wastewater flow and allows grease to cool, solidify, and float to the top where it's retained. Solids and food particles settle to the bottom. Only relatively clean water passes through to the sewer. The trap needs regular pumping—frequency depends on size, usage, and local code, but commercial kitchens typically need service every 1 to 3 months.

They're mandatory in most jurisdictions for restaurants, cafeterias, hotels, and any commercial food service, and required by code in many areas for residential multi-unit buildings. Neglecting them causes blockages downstream, municipal sewer backups, and hefty fines. Size matters: undersizing creates constant overflow and defeats the purpose; oversizing wastes money but doesn't hurt performance.

Grease interceptor is the technical term for the same device, often used interchangeably. When a trap fails, grease lines freeze solid in winter, clogs develop in the main sewer, and you're looking at expensive lateral cleaning or replacement. Proper maintenance is cheaper than the alternative.