Abstract: The present invention refers to a closet combined with a sewage tank (7). The closet comprises a stand enclosing the sewage tank (7) and supporting a chair (1) composed of closet bowl (3), closet seat (4) and closet cover (5). A flushing water tank (18) is connected to the closet. The closet bowl (3) is adapted to be closed in a pressure-tight manner by means of the closet cover (5) and is provided with a discharge valve (8) opening at a predetermined overpressure in the closed closet bowl (3). Means (24, 25, 31) comprising an air-pump (24) are provided to empty the closet bowl (3). By means of the air-pump (24) and said means (25, 31) simultaneously both the closet bowl (3) and the flushing water tank (18) are placed under overpressure. A member (21) is provided to supply flushing liquid from the flushing water tank (18) to the closet bowl (3) when the discharge valve ( 8) in the closet bowl (3) has been opened and the overpressure therein has been reduced.