In the title compound, C(20)H(17)Cl(3)O(5)·H(2)O, the nidulin mol-ecule consists of three rings, the folded central dioxepin-11-one ring being fused on both sides to phenyl rings. The mol-ecular structure is stabilized by intra-molecular O-H⋯Cl and C-H⋯Cl hydrogen bonds that generate S(6) ring motifs. The crystal structure is stabilized by inter-molecular O-H⋯O and O-H⋯(O,O) hydrogen bonds mediated by two inversion-related water mol-ecules, generating R(4) (2)(8) ring and C(2) (2)(4) chain motifs. Weak inter-molecular Cl⋯O halogen bonds are also present with Cl⋯O distances of 3.071 (1) and 3.182 (2) Å.