What is a grease trap? Grease traps (also known as grease interceptors, grease recovery devices and grease converters) are plumbing devices designed to intercept most greases and solids before they enter a wastewater disposal system. Restaurant and foodservice kitchens produce a lot of waste grease which is present in the drain lines from the various sinks dishwashers and commercial woks. If not removed the grease will congeal within the sewer and cause blockage, back-ups, and overflows. It is important to maintain your grease trap clean. The local wastewater collection system communities have set up inspection programs to ensure that these grease traps and/or interceptors are being maintained on a routine basis.