A grease trap (also known as grease interceptor, grease recovery device and grease converter) is a plumbing device (a type of trap) designed to intercept most greases and solids before they enter a wastewater disposal system. Large amounts of oil from food preparation in restaurants can overwhelm a septic tank or treatment facility, releasing untreated sewage into the environment. High-viscosity fats and cooking grease such as lard solidify when cooled, and can combine with other disposed solids to block drain pipes.

Grease traps reduce the amount of fats, oils and greases (FOGs) that enter sewers. They are boxes within the drain run that flows between the sinks in a kitchen to the sewer system. They only have kitchen wastewater flowing through them, and do not serve any other drainage system, such as toilets. They can be made from many different materials, such as stainless steel, plastics, concrete & cast iron. They range from 5 gallons up to 3000 gallons and larger. They can be located above ground, below ground, inside the kitchen or outside the building.

Regular grease trap pumping is critically important to prevent costly plumbing repairs, sewer line clogs and bed smells.