A method of flushing a toilet that includes opening a first valve to introduce a first supply of grey water into a passage to prime a siphon; opening a second valve to introduce a second supply of water into a bowl from a tank, the bowl having an outlet that is in fluid communication with an inlet of the passage; closing the first valve to shut off the first supply of water; evacuating the contents of the bowl through an outlet of the passage by way of the siphon generated by the introduction of the first supply of water and the introduction of the second supply of water; and closing the second valve to shut off the second supply of water.