3-Carboxy­methyl-1,3-benzimidazolium-1-acetate monohydrate

The title compound, C(11)H(10)N(2)O(4)·H(2)O, has a zwitterionic structure, in which the benzimidazole ring system is planar, with a maximum deviation of 0.007 (3) Å. The carbox­yl/carboxyl­ate groups adopt a trans configuration. In the crystal structure, inter­molecular O—H⋯O hydrogen bonds involving the hydr­oxy/oxide O atoms link the mol­ecules into a one-dimensional chain. These chains are further linked by O—H⋯O hydrogen bonds involving the water mol­ecules into a two-dimensional network. π–π contacts between the benzimidazole rings [centroid–centroid distance = 3.5716 (4) Å] lead to the formation of a three-dimensional supra­molecular structure.