What is grease trapin construction?

In everyday trade language, a grease trap is the small hydromechanical unit rated in gpm that sits at or near a sink, and a grease interceptor is the large in-ground gravity tank rated in gallons. The plumbing codes now group both under interceptor, split into hydromechanical and gravity types. For an estimator the distinction is the cost structure: a trap is a fixture-like each-count, while a gravity interceptor brings excavation, structure, covers, and a sampling well with it.

Grease-bearing kitchen fixtures: pot and pre-rinse sinks, wok stoves, kettles, and floor drains and floor sinks in cooking and dishwashing areas, with dishwashers handled per local rules (many jurisdictions prohibit dishwashers ahead of small hydromechanical traps because hot detergent water defeats them). Restrooms and other sanitary fixtures must bypass the interceptor entirely, which is why the rough-in carries a dedicated grease waste line alongside the regular sanitary system. The local FOG ordinance gives the binding list.

Local FOG ordinances set the schedule, and many apply the 25 percent rule: pump when accumulated grease and solids reach a quarter of the unit's liquid depth. A high-volume kitchen can hit that in weeks while a small cafe might take months, so the honest answer is measured, not calendar based. For construction estimators this is an operating cost, not a bid item, but the access covers and sampling well that make pumping and inspection possible are bid items.