BACKGROUND OF THE INVENTION
 1. Field of the Invention
 This invention relates generally to plumbing fixtures and systems and, more specifically, to a Toilet Flushing System using Wastewater.
 2. Description of Related Art
 Wastewater, or "gray water" flushing systems have been made in a variety of forms for numerous years. An early example is a "Combination Wash Basin and Toilet Conservation System" disclosed by Medrano, U.S. Pat. No. 4,358,864. While the Medrano system purports to use gray water from a wash basin to flush the toilet, it requires a complex toilet tank/flushing system that is not compatible with an off-the-shelf toilet. Teichroeb, U.S. Pat. No. 5,813,047 for "Toilet Flushing System that Allows use of Gray Water Drained from a Sink" also discloses a system that cannot be implemented in a stock toilet tank.
 Aleman, U.S. Pat. Nos. 4,069,521 and 4,030,144 use a somewhat standard in-toilet equipment, however, does not connect to an adjacent wash basin, but instead requires a specially-installed gray water system for the entire building. Furthermore, there is no freshwater backup water supply for the gray water system to supplement the gray water when there is insufficient gray water available.
 Sanders, et al, U.S. Patent Application Publication No. U.S.07/0174959 and U.S. Pat. No. 6,276,005 for "Water Recycling Device," Rockwell U.S. Pat. No. 5,201,082 for "Gray Water Toilet System," and Kimball, U.S. Pat. No. 5,084,920 for "Water Recycling System" all disclose sophisticated flushing systems that require that the gray water supply system be pressurized (rather than using a gravity-fed water source).
 What is needed, then, is a flushing system for toilets that is easily installed in a conventional toilet tank, and uses gray water from an unpressurized gray water source.
SUMMARY OF THE INVENTION
 In light of the aforementioned problems associated with the prior devices and systems, it is an object of the present invention to provide a Toilet Flushing System using Wastewater. The system should take gray water from a drain pipe interconnecting the drain of an adjacent sink basin and utilize it as flushing water, without the need for a separate pressurized gray water system. The system should be installable into a conventional toilet tank without the need for a specialized toilet. The flushing system would allow for the use of fresh water or gray water for toilet flushing. Water level and flushing action of the system should be controlled by a pair of floats--a release float to release a main float at a release water level, and a main float that rises rapidly upon its release and causes fresh water inlet flow to cease and simultaneously lift the flapper valve to commence toilet flushing.
BRIEF DESCRIPTION OF THE DRAWINGS
 The objects and features of the present invention, which are believed to be novel, are set forth with particularity in the wended claims. The present invention, both as to its organization and manner of operation, together with further objects and advantages, may best be understood by reference to the following description, taken in connection with the accompanying drawings, of which:
 FIGS. 1A and 1B are front and top views, respectively, of a sink and toilet interconnected using a preferred embodiment of the flushing system of the present invention;
 FIG. 2 is a perspective view of a preferred dual-float flushing system of the present invention;
 FIG. 3 is a perspective view of the system of FIGS. 1 and 2 in a pre-fill condition;
 FIG. 4 is a perspective view of the system of FIG. 3 in a float release condition;
 FIG. 5 is a perspective view of the system of FIG. 3 in a flush condition;
 FIG. 6 is a perspective view of the system of FIG. 3 in a float reset condition;
 FIGS. 7A, 7B, 7C and 7D depict the tank water levels corresponding to the conditions of FIGS. 3-6; and
 FIGS. 8A, 8B and 8C depict flushing methods of the prior art systems, a sink-only use with the system of the present invention and a lavatory and sink use.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
 The following description is provided to enable any person skilled in the art to make and use the invention and sets forth the best modes contemplated by the inventor of carrying out his invention. Various modifications, however, will remain readily apparent to those skilled in the art, since the generic principles of the present invention have been defined herein specifically to provide a Toilet Flushing System using Wastewater.
 The present invention can best be understood by initial consideration of FIGS. 1A and 1B. FIGS. 1A and 1B are front and top views, respectively, of a sink 16 and toilet 14 interconnected using a preferred embodiment of the flushing system of the present invention 10. The sink drain 22 feeds into a drain pipe 18 running between the sink basin 16 and the toilet tank 12. Drain water ("gray water") travels via gravity feed from the drain 22 to fill the tank 12. The flushing system 10 of the present invention installs completely within the chamber 62 of the tank 12, and allows the continued use of the flush handle 20. As such, virtually any tank-style toilet 14 can be modified for use with the current system 10. FIG. 2 depicts the technical detail of this novel flushing system 10.
 FIG. 2 is a perspective view of a preferred dual-float flushing system 10 of the present invention. The operable components of the system 10 are preferably attached to a mounting bracket assembly 24 made up of a plurality of rigid members interconnected (either as shown, or in other configurations. The mounting bracket assembly 24 then attaches to the interior of the toilet tank (see FIGS. 1A and 1B).
 The system 10 uses the flapper valve 34 and flush handle 20 of the original toilet's flushing system. In order to interface with a non-pressurized gray water supply source, the system 10 uses a pair of floats (rather than a single float to shut off water flow). Here, the first float simply provides a two-stage tank fill process; the second float actually performs two actions--shutting of the flow of fresh water into the tank, and also opening the flapper valve 34 to release flushing water into the toilet (i.e. thereby flushing the toilet).
 The release float 28 (i.e. the first float) travels up and down along one or more float guides 30. The guides 30 shown here are elongate rigid bars that allow the floats to slide up and down freely.
 A release plunger 36 comprises a rod 38 extending through holes formed in the release float 28 and the main float 26. The top end of the rod 38 has a head 40 that is enlarged so that it will not fit into the hole formed in the release float 28. The bottom end of the rod 38 connects to an L-shaped retaining arm 46 at a pivot point 42. The retaining arm 46 is attached to the lower mounting bracket 25 at pivot point 44. The retaining arm 46 terminates at its distal end in retaining finger 48. There are teeth or other features formed in the main float 26 with which the retaining finger 48 engages in order to prevent the main float 26 from floating upward (i.e. until the retaining finger 48 has disengaged from the teeth in the main float 26. As should be apparent, sliding the rod 38 up and down will cause the retaining arm 48 to pivot about pivot point 44 in a rocking motion. The retaining arm 46 includes weighting or biasing elements that cause the rest position to be with the retaining finger 48 being forced towards the main float 26.
 A shutoff plunger 50 extends upwardly from its rigid attachment to the main float 26. As the main float 26 rises, the shutoff plunger 50 will also rise. As it rises, the plunger 50 will approach the valve retaining arm 51. The valve retaining arm 51 pivotally attached to the mounting bracket assembly 24 by pivot shaft 54, which permits the arm 51 to rock in the direction shown. The arm 51 terminates in a valve retaining finger 52, which can engage the distal end of the valve release arm 56, when the release arm 56 is rotated into the position shown.
 The valve release arm 56 extends out from the flush shaft 58. The flush shaft 58 interconnects the flush handle 20 and the fill valve 60. The fill valve 60 serves to turn on and turn off the fresh water flow coming from the fresh water supply system. As will become clear below upon review of the description in connection with other drawing figures, the system 10 allows for the filling of the toilet tank with gray water (e.g. from an adjacent sink), or alternatively filling with fresh water from the standard fresh water system (normally connected to the toilet tank), when there is insufficient gray water to flush the toilet.
 Finally, there is a flapper chain 32 (or other lanyard or the like) interconnecting the main float 26 and the flapper valve 34, such that when the main float 26 rises sufficiently, it will cause the flapper valve 34 to lift; thereby releasing water from the tank and into the toilet bowl (i.e. flushing the toilet). As should be appreciated, and as will be discussed below, the flushing action is actually managed by the actions of the floats 26 and 28, and not by the flush handle 20. This means that it is the water level within the toilet tank that actives the system 10 to flush, rather than a manually-actuated flush command to the flush handle. FIGS. 3-6 depict the sequential stages of the system 10 during the flushing process.
 FIG. 3 is a perspective view of the system 10 of FIGS. 1 and 2 in a pre-fill condition. As shown here, the water level is insufficient to have caused the release float 28 to rise. The buoyancy of the release float 28 will determine how high the water must reach in the tank chamber 62 before the float 28 begins to rise. The valve retaining finger 52 remains engaged with the valve release arm 56, which keeps the water fill valve 60 in a closed position. The retaining finger 48 is also engaged with the teeth or other feature formed in the main float 26, thereby preventing the main float 26 from floating up the float guides.
 FIG. 4 is a perspective view of the system 10 of FIG. 3 in a float release condition. Here, the water level in the tank chamber 62 has risen sufficiently to cause the release float 28 to float upward until it has reached the head 40 of the release plunger 36. The head 40 has been pulled upwardly by the release float 28, thereby causing the rod 38 to travel upward as well. As discussed above, upward motion of the rod 38 causes the retaining arm 46 to rock backward as shown by the arrow, until such time as the retaining finger 48 disengages from the main float 26. It is at this instant that the main float 26 has been released to float upwardly (the main float 26 is depicted here just as the float 26 is released, but before it floats upwardly towards the release float 28).
 It should be understood that the water filling the tank could be fresh water from the fill valve 60, or it could be from the gray water drain pipe (see FIG. 1). As such, the user can manually flush the toilet using freshwater, or he or she can allow the toilet to flush "automatically" by using the sink until the drain water fills up the toilet tank.
 FIG. 5 is a perspective view of the system 10 of FIG. 3 in a flush condition. The main float 26 has now traveled upwardly, thereby causing the shutoff plunger 50 to also travel upwardly until it drives the end of the valve retaining arm 51 up. The valve retaining arm 51 will rotate as shown by the arrow until the valve retaining finger 52 pulls back off of the end of the valve release arm 56, which allows the spring-biased flush shaft 58 to freely rotate if the user wishes to open the fill valve 60 manually via twisting the flush handle 20 (in the view of the user facing the toilet, counterclockwise/down is the direction to open the valve 60). FIGS. 3 and 4 depict the valve release arm 56 in its locked open position, which would be the position wherein the fill valve 60 is being held open to fill the tank with fresh water. It should now be clear that the tank can also fill while the valve release arm 56 is free (i.e. and the fill valve 60 remains closed).
 FIG. 6 is a perspective view of the system 10 of FIG. 3 in a float reset condition. Here, the fill valve 60 is closed, but since the tank chamber has drained (by flushing), the floats 26 and 28 have slid down the float guides until the retaining finger 48 reengages the main float 26. The system 10 is now ready to flush by either gray water fill or fresh water fill.
 FIGS. 7A, 7B, 7C and 7D depict the tank water levels corresponding to the conditions of FIGS. 3-6. Specifically, FIG. 7A depicts the water level in the tank 12 being at a level to create the condition depicted in FIG. 3. FIG. 7B depicts the tank 12 water at a float release water level 66, such that the system 10 is in the condition of FIG. 4. FIG. 7C depicts the tank 12 water at a flush water level 68, such that the system 10 is in the condition of FIG. 5 and FIG. 7D depicts the tank 12 water at a reset water level 70, such that the system 10 is in the condition of FIG. 6. A comparison of the steps of the instant flushing system to the prior flushing systems is depicted below in connection with FIGS. 8A-8C.
 FIGS. 8A, 8B and 8C depict flushing methods of the prior art systems, a sink-only use with the system of the present invention and a lavatory and sink use. Under the prior art flushing systems 72, the user uses the toilet 102, and then activates the flush lever 104. Activation of the flush lever lifts the flapper valve at the bottom of the tank, causing the toilet to flush 106. Water immediately begins to fill the toilet tank (once the flapper valve drops closed) until the float causes the fill valve to close 108.
 If a user uses the lavatory and the sink in the configuration of the present invention, the following method 74 will commence: the user uses the lavatory 102 and then the sink 110 (i.e. the user does not activate the flushing handle). As the user sends gray water down the sink drain, it will travel through the drain pipe and into the toilet tank 112. The release float will release the main float when the tank water level reaches the release level 114, which allows the main float to float upward until it pulls up on the flapper valve and causes a flush of the toilet 116.
 If the user only uses the lavatory in the configuration of the present invention, the following method 76 commences: the user uses the lavatory 102 and then actuates the flush lever 118, which opens the fill valve to begin filling the toilet tank with water 120. When the tank level reaches the release level, the release float will release the main float 114, and the main float will rise until the flapper valve opens (to flush) and also releases the valve retaining finger so that the water valve is allowed to close 122.
 Those skilled in the art will appreciate that various adaptations and modifications of the just-described preferred embodiment can be configured without departing from the scope and spirit of the invention. Therefore, it is to be understood that, within the scope of the appended claims, the invention may be practiced other than as specifically described herein.