Abstract: An apparatus for controlling the flow of liquid from a conduit into a tank to maintain a selected level, which is an improvement on the conventional type of float-operated flow valves which use a diaphragm clamped between two flanges and positioned over the end of the conduit through which liquid is supplied at a selected pressure. There is a small opening in the center of the diaphragm and there is a second small opening in the second flange of the flow means. The improvement of this invention, is the use, instead of a float mechanism, a pressure-sensitive diaphragm which is responsive to the hydrostatic pressure in the liquid at the level of immersion of the diaphragm. The diaphragm is adapted to close and open the second small opening, and thus to control the flow through the first valve.