Abstract: An aerator fitting for coupling waste source piping to a single stack drainage system includes a stack inlet and a stack outlet spaced along a central axis from the stack inlet. An offset chamber fluidly coupling the stack inlet and the stack outlet is offset from the central axis in a direction along an offset axis perpendicular to the central axis. A waste inlet in fluid communication with the stack outlet opens in a direction angled relative to the offset axis. A baffle defines a surface inline with the stack outlet angled toward the waste inlet.