an incremental dual stage water - flush toilet has been developed to serve as a means of reducing to an absolute minimum the amount of water used in a water - flush type toilet . the toilet is comprised of a trapless toilet bowl with spring - loaded air valves over a pipe trap below floor level , and a water storage tank divided into a small and large compartments . an incremental flushing mechanism allows conventional type manual flushing of the toilet but will allow enough water to run into the bowl to cleanse the bowl and wash waste into the pipe trap below for interim retention . after multiple incremental flushings of that limited type , a major bowl flush containing enough water to clear the toilet bowl and also to wash all retained waste in the pipe trap into the available sewer line occurs . the sequence of smaller flushings with a larger flushing is again repeatable .