The asymmetric unit of the title compound, C(16)H(10)O(8)·2H(2)O, contains one-half of the centrosymmetric organic mol-ecule and one water mol-ecule. The dihedral angles between the carboxyl-ate groups and the adjacent phenyl ring are 71.31 (3) and 16.67 (3)°, while the carboxyl-ate groups are oriented at a dihedral angle of 72.01 (3)°. In the crystal structure, inter-molecular O-H⋯O and bifurcated O-H⋯(O,O) hydrogen bonds link the mol-ecules to form a three-dimensional supra-molecular network.