Abstract: A vacuum flush waste disposal system for aircraft; wherein, the required vacuum is acquired at altitude through the differential pressure between the aircraft cabin pressure and the ambient pressure above approximately 15,000 feet. When the aircraft is below this altitude or on the ground, the vacuum is provided by a blower. For flushing the toilet bowl, a timing device is initially actuated and functions: to introduce a recirculated flush fluid into a flush ring in the upper portion of the toilet bowl; and to open a drain in the lower portion of the toilet bowl, leading to the vacuum waste line; whereby, the waste and flush water are rapidly propelled through the waste line towards a centrally located holding tank, by the differential pressure acting upon it. Once in the holding tank, the waste fluid is filtered out for further use as the recirculated flush fluid.