In the title compound, C24H27N3O5·H2O, the essentially planar benzimidazole ring system [maximum deviation = 0.020 (1) Å] forms dihedral angles of 54.10 (11) and 67.79 (6)°, respectively, with the mean plane of pyrrolidin-2-one ring and the benzene ring. The pyrrolidin-2-one ring adopts an envelope conformation with one of the methylene C atoms at the flap. An intramolecular C—Hπ interaction is observed. In the crystal, O—HO and O—HN hydrogen bonds link the two components into a double-tape structure along the a axis. The crystal packing is further stabilized by weak π–π stacking [centroid–centroid distance = 3.6632 (9) Å] and C—HO interactions.