PURPOSE: To prevent a slab material, which is cast on a spring water treatment panel main body laid out on a lower part slab, from falling to the lower part slab from a clearance between the edge of the spring water treatment panel main body and a vertical wall or a post of a spring water treatment tank only with the spring water treatment panel main body.

CONSTITUTION: A linear folding recessed groove 4 is formed on a fastened area 3 of a panel main body 1 which forms recessed legs 2 at a definite span. The panel main body 1 is folded by the folding recessed groove 4 at a right angle. One side is installed to a lower part slab while the other side is installed at a vertical wall. This constitution makes it possible to prevent an upper part slab material cast from falling down to a lower part slab from a clearance between a side edge of the spring water treatment panel main body 1 and a vertical wall of a spring water treatment tank.