Abstract: The invention provides a toilet flushing system comprising a water reservoir provided with a water inlet, and a water outlet for directing water into or towards an associated toilet bowl; a discharge chamber communicating with the discharge outlet of the toilet bowl, the discharge chamber having at a downstream location thereof an exit opening provided with closure means; and air conduit extending between an upper end of the water reservoir and the discharge chamber such that reductions in air pressure within the upper end of the water reservoir caused by a fall in water level in the water reservoir are transmitted to the discharge chamber to produce temporarily a partial vacuum therein thereby to draw water from the toilet bowl through the discharge chamber.