Back-flush filtering apparatus, particularly for a house water supply system

An improved liquid filtering device of the type having a housing, the housing having an inlet connection and an outlet connection for respectively receiving and discharging a flow of liquid to be filtered, a cylindrical filter element mounted in the housing intermediate the inlet connection and the outlet connection, the cylindrical filter element having filtering apertures extending therethrough at longitudinally and circumferentially spaced intervals between a cylindrical outer surface and a cylindrical inner surface, the housing having an internal first passage for passing the flow of liquid from the inlet connection to the cylindrical outer surface and an internal second passage for passing the flow of liquid from the inlet connection to the inner cylindrical surface, movable means in the housing for alternatively diverting the flow from the inlet connection to one of the first and second passages, the improvement comprising, in combination therewith, spray means rotatably mounted within the cylindrical filter member for receiving the flow from the second passage and rotatably spraying the flow against the cylindrical inner surface, and wherein the movable means includes an elongated tubular extension having an extension passage extending therethrough, and sleeve means movably mounted to said elongated tubular extension for alternatively clearing said extension passage to permit the passage of flow from the inlet connection to outlet connection and closing said extension passage to prevent the passage of flow from the inlet connection to the outlet connection, said sleeve means being operable to clear and close said extension passage responsive to the position of tubular extension.