PURPOSE: To install a hydro-electric power plant on deep sea, by pushing a tapered screw discharge pipe having suction port larger than delivery port into high pressure sea while applying pressure thereby discharging waste water without hindering drainage of turbine.

CONSTITUTION: When generating power through utilization of high ressure sea water at deep position, waste water is pressure discharged by lengthening the screw discharge pipe 19 while making the suction port larger than the delivery port and tapering together with the screw blade 29 then rotating the screw wheel 7 and applying pressure onto said waste water toward the delivery port thus to treat waste water without hindering drainage of turbine. Consequently, hydro-electric power station can be installed even at deep position resulting in development of substitutive energy source utilizing endless sea water pressure.