PURPOSE: To accumulate negative pressure generated in the upper part of a pipe and enable negative pressure energy to be utilized, by forming a bottom end part of the introducing pipe, inserted into a well cylinder from a clear water storage tank, to be flexed while positioning a mouth part of the pipe to an underground water level of the well cylinder and controlling a flow of clear water.

CONSTITUTION: A device provides a clear water storage tank 1, set adjacent to a ground surface A, and an introducing pipe 3 introducing clear water from the clear water storage tank 1 into a well cylinder 2 embedded by excavating the ground reaching an underground water tank B. And a bottom end part 4 of the clear water introducing pipe 3, inserted into the well cylinder 2, is formed to be flexed in a J-shape. While a mouth part 5 of the pipe is positioned to an underground water level naturally generated in the well cylinder 2, and if a flow of introduced clear water flow control device 7 provided in the clear water storage tank 1, a negative pressure is generated in an upper part 8 of the introducing pipe 3. The device, accumulating this negative pressure energy to be stored in a tank C set to a separate place, enables the negative pressure energy to be used as necessary. In this way, the necessary negative pressure energy can be obtained by only using a simplified equipment and method.