PURPOSE: To reduce the cost of construction work by a method in which a water-liftting well is excavated to a depth enough to pass through the clay layer, a water-stop board is provided in the clay position within the well, and groundwater coming out above the water stop board is injected under pressures below the waterstop board.

CONSTITUTION: Spring water coming out of the layer above a clay layer 1 flows through the slits of a water-lifting screen 8 into a water-lifting well 11 and is stored in a water-stop board 6. The spring water is then taken into a water-lifting pipe 12 by a pump 13, partly sent out through a sluice valve 20b to a pipe 22, and partly sent through a sluice valve 20a into a water supply pipe 15. The spring water passes through the pipe 15, is discharged through a screen 17 into a water supply chamber 16, and then injected under pressures through a water supply screen 4 and gravels 5 into the stratum lower than the clay layer 1.