Abstract: A lavatory system suitable for use on a commercial passenger aircraft includes at least one toilet bowl for receiving waste and a waste-holding tank in fluid communication with said toilet bowl for receiving waste from said toilet bowl. The waste-holding tank is kept at a pressure less than the ambient pressure surrounding the toilet bowl so that waste from the toilet bowl is drawn to the tank by the difference in pressure. A flush valve is provided in the drain line between the toilet bowl and the waste-holding tank and is selectively operable to pass the toilet bowl contents into the waste-holding tank. Water from the potable water supply system is provided to the toilet bowl to wash the sides of the toilet bowl and to assist in moving the waste material to the drain line. A water inlet valve is provided to selectively control the introduction of water into the toilet bowl and preferably the water inlet valve and flush valve are operated in a timed sequence by actuation of a single flushing switch.