An apparatus for separating FOG from grey water in an effluent includes a housing having a first end having two plumbing fittings and a second end having one plumbing fitting. A baffle mounted inside the housing at the second end forms a barrier to flow of liquid toward the plumbing fitting on the second end above a certain height, and allows the flow of liquid past the barrier toward the plumbing fitting on the second end below the certain height. A conduit allows flow of liquid from past the baffle to one of the plumbing fittings on the first end. A plug closes one of the three plumbing fittings, and leaves the other two plumbing fittings available for connection to plumbing from a source of effluent and an outlet for grey water, respectively.