Abstract: A compact and portable drain having particular application to recreational vehicles such that sewage contained within a holding tank thereof can be relatively easily and efficiently emptied and disposed of at a sewage dump. The drain is connected between a drain hose and a receptacle at the exterior of the recreational vehicle. The flow of sewage through the drain is controlled by a manually operated, reciprocating valve plate which is positioned to either block or open a flow path through the drain. Thus, the valve plate can be opened so that sewage may be drained from the holding tank to a sewage dump by way of the drain and drain hose. A water inlet is also connected to the drain, so as to permit the holding tank to be flushed and cleaned via the drain once the sewage is removed from the holding tank and the valve plate is closed.