Abstract: The present invention relates to a grease trap system for wastewater systems, having an inlet pipe with a shut off valve, an outlet pipe with a shut off valve and a grease interceptor comprising a replaceable container body including means to trap fats, oils and grease within the body. The body has inlet and outlet slide couplers in opposed walls, and each coupler has an associated connecting means to sealingly fluidly connect the slide couplers to the inlet and outlet pipes. When the container body is disconnected from the pipes the slide couplers may also be sealed by a removable plug for transport. The slide couplers displace inwardly and outwardly relative to the container to give clearance between the pipes to remove the container. A method of replacing full containers with empty containers is also comprehended.