You are an expert at summarizing long articles. Proceed to summarize the following text:

You are an expert at summarizing long articles. Proceed to summarize the following text: 
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to a water saving device for a toilet and more particularly to a water saving which may be installed in the toilet at the factory or which may be added to an existing toilet to conserve water during the flushing thereof. 
     2. Description of the Related Art 
     In the United States, approximately 40% of all domestic water consumed is flushed down the toilet. One person using a 5.5 gallon flush toilet will use 13,000 gallons of fresh water per year to dispose of 165 gallons of body waste. Since all water from the toilet goes directly into the sewer or septic tank, saving water used by toilets reduces both consumption and waste water flow. 
     One common approach to retrofitting older toilets to conserve water is to install a displacement device. Toilet displacement devices such as bricks or the like are used primarily on non-conserving toilets in order to reduce the volume of water used each time the toilet is flushed. This type of displacement device is simply placed into the tank in places where they do not interfere with the function of the flushing mechanism. The volume, which they occupy, will be saved each time the toilet is flushed. 
     SUMMARY OF THE INVENTION 
     A water saving device is described which is used in combination with a flush toilet system of conventional design. The conventional flush toilet system includes a water tank having a drain opening formed in the bottom thereof with a valve seat positioned in the drain opening. A fill valve assembly is positioned in the water tank and has an inlet connected to a source of water under pressure. A float is operatively connected to the fill valve assembly for controlling the operation thereof. A toilet bowl is provided below the water tank and is fluidly connected to the water tank by the drain opening and the valve seat. An overflow tube is also provided in the water tank and has an open upper end and a lower end which is in communication with the drain opening. A flapper valve is positioned in the water tank and is moveable between a lower closed position wherein it is in sealing engagement with the valve seat to an upper position wherein water in the water tank will drain into the toilet bowl. A flush handle is moveably mounted on the water tank and is operatively connected to the flapper valve for raising the flapper from its lower closed position. 
     The water saving device of this invention comprises a flapper valve limit structure which yieldably limits the upward movement of the flapper valve after it has been moved upwardly from its lower closed position towards its upper position thereby reducing the amount of water which will be discharged from the water tank into the toilet bowl during a flushing cycle. In the preferred embodiment, the flapper valve limit structure includes a clip which is mounted on the overflow tube and which has a spring attached thereto and extending therefrom. A flapper valve engagement member is secured to the outer end of the spring which is in the path of the flapper valve as it moves upwardly from its lower closed position towards its upper position. Preferably, the clip is selectively vertically moveably mounted on the overflow tube. 
     It is therefore a principal object of the invention to provide a water saving device for a toilet. 
     Still another object of the invention is to provide a water saving device for a toilet which may be either factory installed or which may be retrofitted into a water tank of the flush toilet system. 
     Still another object of the invention is to provide a water saving device for a toilet wherein a flapper valve limit structure is secured to the overflow tube in the water tank and which is in the path of the flapper valve to limit the amount of vertical movement of the flapper valve during a flush cycle. 
     These and other objects will be apparent to those skilled in the art. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a front view of a conventional toilet tank of a toilet flush system with portions cut away to more fully illustrate the invention: 
         FIG. 2  is perspective view of the water saving device of this invention: 
         FIG. 3  is a partial enlarged perspective view of a portion of the device of  FIG. 2 : 
         FIG. 4  is a view similar to  FIG. 1  except that the water saving device of this invention has been mounted on the overflow tube; and 
         FIG. 5  is a side view of the water saving device of this invention mounted on the overflow tube of the toilet tank which illustrates the water saving device limiting the upward movement of the flapper valve. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to  FIG. 1  which illustrates a conventional prior art toilet flushing system  10 , the system  10  includes a water tank  12  having a water inlet  14  and a water drain opening  16  formed in the bottom thereof. An upstanding fill valve assembly  18  has its lower end  20  positioned in the inlet  14  and secured thereto by a lock nut and coupling assembly  22  for connection to a water inlet line  24 . Float rod  26  is operatively connected to the valve assembly  28  and extends therefrom. Float ball  30  is secured to the outer end of rod  26  in conventional fashion. The fill valve assembly  18  includes a water fill line  31  which extends downwardly into the tank  12  from the discharge side of the valve assembly  28  for refilling the tank  12  after each flush. An overflow tube  32  is positioned in the tank  12  and has its lower end in communication with the toilet bowl. A refill tube  34  extends from the discharge side of the valve assembly  28  to the upper end of overflow tube  32  to refill the toilet bowl after each flush. 
     A drain fixture  36  is mounted in the drain opening  16  and includes an annular valve seat  38  at its upper end which is normally closed by a conventional flapper valve  40  which is pivotally secured to the overflow tube  32  in conventional fashion. When in its closed position, as illustrated in  FIG. 1 , flapper valve  40  closes the valve seat  38 . When its open position, as illustrated by broken lines in  FIG. 1 , flapper valve  40  is unseated from valve seat  38  so that water in the tank  12  may pass through the drain fixture  36  into the toilet bowl to flush the same. 
     A conventional flush lever  42  is rotatably mounted on the tank  12  at the upper end thereof and has a conventional trip lever  44  connected thereto. Chain  46  extends from trip lever  44  to the flapper valve  40 . When the flush lever  42  is in its normal non-flush position, as illustrated in  FIG. 1 , the chain  46  will be slack and flapper valve  40  will be closed. When flush lever  42  is pivotally moved downwardly from its non-flushing position, as illustrated by the arrow in  FIG. 1 , trip lever  44  will be moved upwardly which causes the chain  46  to lift flapper valve  40  out of sealing engagement with the valve seat  38 . As the chain  46  lifts flapper valve  40  from its closed position, the buoyancy of the flapper valve  40  causes it to remain in its raised position until the water level in the tank  12  drops to a level where the flapper valve  40  is no longer floating in the water and it will drop downwardly, by gravity, to its lower seating position on the valve seat  38  of drain fixture  36 . In the conventional toilet tank  12 , substantially all the water in the tank  12  will be drained therefrom during each flush cycle. The instant invention permits a flushing cycle to occur with a reduced amount of water being drained from the tank  12  preventing water waste and reducing the amount of waste water being flushed into a septic tank or the like. 
     The water saving device of this invention is referred to generally by the reference numeral  48 . Device  48  includes a spring clip or bracket  50  which is adapted to be selectively vertically adjustably mounted on the overflow tube  32 . Clip  50  includes a semi-circular base portion  52  provided thereon. The numeral  54  refers to an elongated coil spring having ends  56  and  58 . Although other types of springs may be utilized, it is preferred that the spring  54  be of the coil-type as illustrated in  FIG. 2 . End  56  of spring  54  is secured to the semi-circular portion  52  as illustrated in  FIGS. 2 and 3  so that end  56  of spring  54  is rigidly attached to the semi-circular portion  52 . End  58  of spring  54  is secured to a flapper valve engagement member  60  which is preferably constructed of a plastic or neoprene material. Preferably, the engagement member  60  includes a base portion  62 . 
     In use, the clip or bracket  50  is vertically adjustably mounted on the overflow tube  32  so that the engagement member  60  is positioned above the flapper valve  40  and is in the pivotal path thereof as illustrated in  FIGS. 4 and 5 . The positioning of the device  48  relative to the overflow tube  32  is selected to control the amount of water which will be flushed from the tank  12  during each flush cycle. 
     Assuming that the flapper valve  40  is in its closed position, as illustrated in  FIG. 4 , the toilet is flushed as follows. The flush lever  42  is pivotally moved downwardly as indicated by the arrow in  FIG. 4  which will cause the trip lever  44  to move upwardly so that the chain  46  will lift the flapper valve  40  from its sealing engagement with valve seat  38  and will move the flapper valve  40  upwardly from its lower closed position towards its upper position until the flapper valve  40  engages the engagement member  60  of the device  54  which will be sensed by the person who will hold the lever  42  downwardly till the person senses the engagement of the flapper valve  40  against the device  54  and will hold that position for a second or two during which time water will be draining from the tank  12  into the toilet bowl. The person will then release the lever  42  which will cause the flapper valve  40  to drop downwardly, by gravity, into sealing engagement with the valve seat  38 . 
     Thus, it can be seen that the toilet may be flushed utilizing a limited amount of water due to the positioning and the yieldable resistance of the water saving device  48  being in the pivotal path of the flapper valve  40 . If it is desired to more completely flush the water from the tank  12 , the lever  42  will be depressed downwardly to its lower limit which will cause the flapper valve  40  to move the engagement member  60  of the device  54  upwardly from the broken line position of  FIG. 4  which means that additional water will be flushed from the tank  12 . 
     Thus it can be seen that a novel water saving device has been provided which may be retrofitted onto existing tanks of toilets or which may be factory installed. It can therefore be seen that a novel water saving device has been provided for a toilet flush system which accomplishes all of the stated objectives.

Summary:
A water saving device for a flush toilet comprising a flapper valve limit structure which yieldably limits the upward movement of a toilet tank flapper valve after it has been moved upwardly from its lower closed position towards its upper position thereby reducing the amount of water which will be discharged from the water tank into the toilet bowl during a flushing cycle.