A fill valve with pressure chamber having an open bottom end and a diaphragm at a top end such that falling water level in the toilet tank causes the diaphragm to flex in a first direction, thereby moving a sealing member to an open position, with a venturi in the fill valve keeping the sealing member in the open position until water refilling the tank causes the diaphragm to flex in a second direction, thereby moving the sealing member back to the closed position.