US Patent 7753065 Hydrant backflow restriction system

A hydrant backflow prevention system comprises a backflow prevention valve, operably coupleable to a hydrant to restrict passage of materials through the hydrant into a water supply feeding the hydrant. The backflow prevention valve is installable fluidly inline with the water supply at a location below which an upper dry barrel of the hydrant is coupled to a water delivery system. The backflow restriction valve is operable to substantially restrict backflow into the water supply when in a closed position, and allow flow of water through the hydrant when in the open position.