UNDERGROUND WATER STORAGE TANK

摘要

PROBLEM TO BE SOLVED: To provide an underground water storage tank capable of suppressing construction cost than before because a permeable sheet is provided on the internal wall surface of a maintenance passageway and rainwater is stored via the permeable sheet, capable of surely removing unnecessary objects in rainwater even if a burying site is restricted, and capable of allowing the removing work to be efficiently performed.SOLUTION: An underground water storage tank buried and used underground includes at least: a water storage unit in which a water storage block group configured by stacking a plurality of water storage blocks is liquid-tightly covered by a covering material; and a rainwater lead-in pipe for leading rainwater into the water storage unit. The water storage unit is provided with a passageway constituting member having a maintenance passageway extending in a horizontal direction at least in a part of the water storage block group, and a permeable sheet is provided on the internal wall surface of the maintenance passageway. The rainwater lead-in pipe communicates into the maintenance passageway of the passageway constituting member.