Energy-saving building water circulation system

The utility model discloses an energy-saving building water circulation system. The device comprises a water collecting tank arranged around a roof, an upper water accumulation groove is formed in theridge; an opening of the water collecting tank is covered with a protective net; water outlets are formed in two sides of the upper water accumulation tank; a floating ball valve is arranged on the upper water accumulation tank; the floating ball valve comprises a valve mounted on the water outlet and a floating ball positioned in the upper water accumulation tank and used for controlling the valve to be opened and closed; a rotating device is arranged between the protective net water collecting tanks; a water outlet is formed in the bottom of the water collecting tank; the drain outlet is connected with a filter box through a drain pipe; water utilization mechanism arranged in building, the bottom of the filter box is higher than the water mechanism; when a certain amount of water is discharged from the water ou