1.  Field of the Invention
This invention relates to valves that control the flow of water from the outlet of the toilet water reservoir.  More particularly, the invention relates to valves that prevent water leaks from such reservoir outlet.  In addition, this invention relates to valves which control the amount of water which is permitted to exit from the toilet reservoir.  More particularly, the invention relates to adjustable valves which can be customized to permit only a preset amount of water to exit from the outlet of the reservoir.  Moreover, this invention relates to valves which prevent the undesirable continuous flow of water to the toilet bowl which results from valve malfunction.  More particularly, this invention returns the flushing lever to its OFF position, such that it cannot get stuck in a flush position causing continuous water flow to the toilet bowl. 
2.  Description of the Related Art
Toilet flushing systems which comprise a conventional outlet control valve suffer from water drips.  Variations in the design of the outlet valve are unable to prevent such drips.  One way to design a long lasting valve, which will not easily erode, is to design it rigid and heavy.  Yet, such design is defective because in case dirt accumulates at the outlet the valve will not be able to seal the outlet due to its rigidity.  Thus, water will drip from between the outlet and the valve.  A second design for such outlet valve is to make it soft and flexible, in order for the valve to seal the outlet even when dirt accumulates at the outlet.  Yet, such design is defective for two reasons.  First, soft valves easily erode in water, such that their shape changes, preventing their ability to seal the outlet.  Second, soft valves are light in weight which hinders their ability to tightly seal the outlet.  Any variation in water pressure in the reservoir causes their position to be easily disturbed. 
Both the soft and hard valves are supposed to seal the outlet by gravity force acting on the outlet.  Such gravity force is proportional to the weight of the water column acting on the valve's surface plus the valve's weight.  Relying on the weight of the water to tightly keep the valve in place is not sufficient.  In addition, since the valve's heavy weight results in its inflexibility, there is a tension between the need to design the valve heavy enough to tightly seal, yet, light enough to be flexible to fit the outlet even when there is dirt.  Thus, since relying on the gravity force of the water column above the valve plus the weight of the valve is problematic, a more reliable method is needed in order for the valve to tightly seal the outlet. 
Accordingly, it is the object of the present invention to provide a toilet valve which can tightly seal the reservoir's outlet even under conditions of dirt and erosion of the valve.  More specifically, it is the object of this invention to provide a toilet reservoir outlet valve which is tightly seated against the outlet by hydraulic force, where such hydraulic force is greater than the gravity force conventionally relied upon. 
It is an additional object of the present invention to provide an outlet valve which can be adjusted to control the quantity of water which can be flushed. 
It is yet an additional object of the present invention to provide a mechanism which returns the flushing lever to its OFF position, such that it cannot get stuck in a flush position, resulting in the undesirable continuous flow of water to the toilet bowl.