An apparatus and method for a grease trap for separating grease and solid waste from waste water. The grease trap includes a tank having a downwardly shaped bottom. An upwardly shaped baffle insert divides the tank into an upper chamber and a lower chamber. An outlet port near an upper part of the baffle allows waste into the upper chamber. An inlet invert in the tank receives incoming waste water, while an outlet invert removes water from the tank. A removable cover covers the tank and allows access for removal of accumulated grease and solid wastes.