Grease traps work using gravity and coalescence as a means of separation. Greases, fats and oils are about 89% - 90% of the weight of water. To separate them from water an interceptor (Grease Trap) provides a separation chamber, which allows FOG, the acronym for ‘fats, oils and grease’, to rise to the surface. FOG-free water then exits from the separation chamber at the low point, farthest from the inlet end.