PURPOSE: To obtain tanks for potable water and nonpotable water and a small-sized irrigation reservoir having merit of prestressed structure and constructible in short period of time at low costs by a method wherein precast concrete wall panels are erected in a circle and are tightly bonded together into a wall body with prestressing introduced in the circumferential direction thereof, and a bottom is constructed of a buffering layer bed and a waterproofing sheet layer that is laid over said layer bed.

CONSTITUTION: Natural ground is excavated in a circle and foundation 2 is provided to peripheral edge thereof, and wall panels 1 are erected on the foundation. Joints between the panels are filled with jointing materials. At the same time, PC steel wires 4 are inserted through sheath pipes 3, crossing over adjoining wall panels 1, and tension is applied thereto and prestressing is introduced therewith in the circumferential direction, and then the wall panels 1 are tightly bonded to form a wall body. Works for providing a mud discharge pit 13, a mud discharge pipe 14, a drain material 15 and an air breather pipe 16 are executed in parallel with the above-mentioned works. A sand layer bed 9 is provided over the excavated ground 8 and after rolling is applied over the sand layer 9, a waterproofing sheet layer 10 is laid thereon, and peripheral edge of the sheet layer is fixed by adhesion or with anchor bolts 12 to the surface of lower end flanges of the well panels 1, and thereby the bottom is constructed.