in one embodiment of the present system invention , there is provided a dividing module positioned in the holding tank of a toilet to separate the holding tank into a main portion and a reserve portion . the dividing module has a height lower than the full water level in the holding tank . the dividing module includes the ability to selectively connect the main portion and the reserve portion in fluid communication of each other . the embodiment allows an operator to press the handle arm an initial time to maintain the main portion and the reserve portion in substantially fluid separation of each other , such that water in the main portion is utilized to flush the toilet and wherein when the operator presses the handle a second time in the same manner as the initial time , the dividing module connects the main portion and the reserve portion in substantially fluid communication with each other , such that water in the reserve portion and the main portion is utilized to flush the toilet .