Abstract: An improved sealing mechanism for closing the bottom opening of a toilet bowl and adapted to be moved between open and closed positions with a minimum of human effort. The mechanism includes a movable blade and an elastic seal in the form of a curtain that functions to wipe foreign material from the blade when the latter is moved between open and closed positions, the curtain also functioning to provide a seal when the blade is in its closed position. The blade is supported so that when in its closed position it will always align itself with respect to the curtain to maintain an optimum seal. The blade is pivotally supported on an arm of a vertically disposed crank which is spring-actuated to an upper position and which can be depressed and pivoted for moving the blade between its closed and open positions.