In the title compound, C14H16N2O4·H2O, three substituent groups are located on the same side of the benzimidazole ring plane. In the crystal, O-H⋯O hydrogen bonds and π-π stacking between parallel imidazole rings [centroid-centroid distance = 3.858 (4) Å] link the mol-ecules into a three-dimensional supra-molecular structure.