Improvements in an Overflow Shutoff Valve (OSV) that is designed to automatically shutoff water flow when water flows above a rated amount. It is a self-cleaning design with automatic resetting function. The valve consists of an outer body with an inlet and outlet port with an internally installed rubber Venturi tube assembly, fixed flange, moving flange, coil spring and surge flow suppressing orifice. The lower pressure causes the rubber tube to be squeezed by the water pressure, and then automatically shuts off the valve. When the supply water pressure drops below 5 psi the Overflow Shutoff Valve automatically resets and opens to normal position. A flow suppressor orifice prevents any surge flow or start up flow which could cause premature shutoff of the valve. The Overflow shutoff valve can be installed in-line or in a Y body shutoff valve for easy service.