In the title compound, C(14)H(10)O(4)·H(2)O, isolated from the roots of Calophyllum membranaceum, the xanthene ring system is almost planar (r.m.s. deviation = 0.008 Å). In the crystal structure, inter-molecular O-H⋯O and O-H⋯(O,O) hydrogen bonds connect the mol-ecules.