Abstract: An improved flushing valve for inter-connecting a water closet with a waste dispensing bowl for preventing overflow in the event of a line stoppage. The valve is opened in the ordinary manner and held open by the action of fluid flowing through the valve onto a floatable member having a positive buoyancy that maintains the valve in an open condition in the presence of fluid flow. In the absence of a fluid flow, the valve is allowed to close. In the presence of a line stoppage, overflow fluid will tend to back up causing the floatable member having a positive buoyancy to release the valve which is allowed to close thereby preventing discharge of any further fluid from the water closet. All attempts to operate the water valve will fail as long as the floatable member is held in a floatable condition by the overflow fluid.