Patent ID: 8028713

Claim:
An underground water storage tank configured to be buried underground and to be capable of storing water therein, characterized in that said underground water storage tank comprises: an internal water storage sub-tank provided by coating an assembly of water-bearing materials obtained by combining multiple water-bearing materials with one another with a first water-impermeable sheet; soil pressure absorption plates for absorbing soil pressure from the surroundings of the underground water storage tank provided outside said internal water storage sub-tank; and a second water-impermeable sheet for coating said soil pressure absorption plates so as to prevent water stored in the internal water storage sub-tank leaking to the exterior, and wherein an outer water storage compartment including said soil pressure absorption plates is defined between said first water-impermeable sheet and said second water-impermeable sheet; multiple vertical pipes, and coupling pipes for coupling said vertical pipes to one another, wherein one or more first intake pipes, each having one end communicated to said internal water storage sub-tank and the other end opened into said outer water storage compartment, are provided to penetrate through said first water-impermeable sheet; said first intake pipe is provided with a first non-return valve configured to allow water to flow from said outer water storage compartment into the interior of each internal water storage sub-tank when a water pressure of said outer water storage compartment is equal to or higher than a water pressure within the internal water storage sub-tank; and prevent water from flowing from the interior of the internal water storage sub-tank to said outer water storage compartment when a water pressure of said outer water storage compartment is below a water pressure within the or each internal water storage sub-tank, and wherein said vertical pipes and said coupling pipes are embedded in said soil pressure absorption plates; wherein said first intake pipe is provided through said first water-impermeable sheet so that the other end of said first intake pipe is opened into the interior of an applicable one of said vertical pipes; and wherein said first non-return valve is provided at the other end of said first intake pipe inside said applicable vertical pipe.