although efficient vacuum toilets create a loud noise level during the flush cycle due to the amount of vacuum that needs to be applied in order to cause the septic waste to travel from the toilet basin to the holding tank accordingly the present assignee has sought to reduce the noise associated with vacuum flushing by providing a two stage flush system described in u s ser no 13 804 539 titled u201c two stage flush and grey water flush systems and devices u201d incorporated herein by reference the present inventors have sought various ways to improve the features of the two stage flush system and its related components as shown in fig1 there is provided a two stage flush that uses a single transient tank 144 positioned between nearby lavatories this allows the two lavatories to be serviced by the single transient tank 144 the single transient tank 144 may be positioned in fluid communication between one or more toilet bowls and the main aircraft waste tank this tank 144 holds waste from one or more a first stage flushes until the tank 144 becomes so full as to require emptying this first stage flush reduces the noise level associated with the flush process because a lesser vacuum is demanded for the first stage of the flush in order to deliver the waste to tank 144 once emptying of the tank 144 is necessary a second stage flush applies vacuum through a transfer valve 146 that delivers the waste to the on board waste tank any of the embodiments described above may be.