20% 2. at night, water is pumped from a treatment plant reservoir through distribution piping to an elevated storage tank. the water surface in the supply reservoir is at 10-ft elevation; the lift-pump elevation is 20 ft; the water level in the elevated tank is at 140 ft elevation. the pipe network may be considered equivalent to 5000 ft of 10-in diameter cast-iron pipe (c = 100). calculate the pump discharge pressure needed to supply a flow of 1000 gals/min to the tank.