A grease trap is a collection device connected into the drain lines between the kitchen sinks and the outflow lines to the sewer system.
Its function is to reduce the flow rate of grease laden water, delaying it within a confined chamber, thus allowing the grease to rise or float to the surface and be trapped in the liquid surface of the chamber while the solids settle to the lower level of the trap. The outflow of the grease trap must be connected to a sanitary or combined sewer.