In the title compound, C(16)H(16)N(2)O(5)·H(2)O, the dihedral angle between the two benzene rings is 25.9 (1)°. Intra-molecular O-H⋯O and N-H⋯O hydrogen bonds are observed. In the crystal, the components are linked into a three-dimensional network by O-H⋯O and O-H⋯(O,O) hydrogen bonds.