Abstract: A vacuum wastewater system for an aircraft includes a collection pipe leading to a collection container, a branch pipe leading from a receptacle, and a Y-shaped pipe junction with an acute entry angle connecting the branch pipe into the collection pipe on a side thereof opposite from the receptacle. The branch pipe crosses over the collection pipe just upstream of the junction. An arcuate pipe bend joins a straight portion of the branch pipe to a straight branch pipe leg of the pipe junction in substantially the same horizontal plane in which the collection pipe extends. This configuration deflects the flow of conveyed material so that centrifugal force holds the material along the pipe wall away from the crotch of the Y-shaped junction. This minimizes the reverse flow against the main conveying direction and deposition and accumulation of material in the collection pipe upstream from the pipe junction.