inflow state again the state of each outer component of the self closing water saving device 70 of the present invention is shown in fig1 and the state of each inner component thereof is shown in fig1 and 120 so far all components of the self closing water saving device 70 of the present invention have begun a next operation cycle additionally the upper edge of the primary valve part a of the float can 59 is designed to be lower than rather than flush with that of the secondary valve part b of the float can 59 in order that water does not flow into both of the primary and second valve parts at the same time when the water level in the tank rises if water flew into both of them at the same time the secondary valve float 66 rotates upwards immediately that is the secondary valve is opened at this time however although the primary valve float 64 rotates upwards at once synchronously the primary valve would not be closed immediately and thus the secondary valve is opened temporarily which leads to temporary outflowing of water out of the jet propelling joint 33 those skilled in the valve art can change the specific inner structure of the present invention by changing the inner components of the valve such as exchanging the positions of the piston assemblies of the primary and secondary valves or either merely the piston assemblies of the primary valves or merely the piston assemblies of secondary valves are used or integrally changing the piston movable structure of the piston assemblies of the primary and secondary valves to a cup movable structure like an inner structure of a common self closing water.