In the title compound, C10H8N3S+·NO3 −·H2O, one of the N atoms of the benzimidazole unit is protonated, unlike than that in the thia­zole group. This protonation leads to equalization of the bond angles at the two N atoms of the benzimidazole group. The benzimidazole and thia­zole systems are almost coplanar, forming a dihedral angle of 0.5 (2)°. In the crystal, the nitrate anion and water mol­ecule bridge the thia­bendazolium cations through N—H⋯O and O—H⋯O hydrogen bonds, leading to a supra­molecular network based on an infinite one-dimensional chain using [001] as base vector.