PURPOSE: To prevent the coming of water percolating into the ground up to the earth surface by a method in which a water storage tank is provided at the top of a percolation pipe buried underground, a pump is provided between the percolation pipe and the water storage tank, and a cut-off plate is attached to the upside of the percolation pipe.

CONSTITUTION: A percolation pipe 1 whose lower part is provided with holes (a) for percolating water is buried underground, and a water storage tank 2 collects rain water or purified water coming from an intake port 4 through a netting 6. A pump 7 provided between the percolation pipe 1 and the water storage tank 2 automatically operates when the amount of water in the water storage tank 2 increases to send the water of the tank 2 to the percolation pipe 1. A cut-off plate 8 attached to the upside of the percolation pipe 1 serves to prevent the coming of percolating water under the ground up to the earth surface.