In the title compound, mu-3,4'-bi-1,2,4-triazole-di-mu-chloro-copper(II) monohydrate, [[CuCl(2)(C(4)H(4)N(6))].H(2)O](n), the Cu atom is located in a distorted octahedron consisting of two N atoms and four Cl atoms. The structural unit is an infinite chain in which octahedral groups, connected by shared edges, are also linked by bitriazole molecules. The bitriazole ligand, the Cu atom and the water O atom all lie on independent twofold axes. The structure is held together by hydrogen bonds between the water molecules and the non-coordinated N atoms of the ligand, and by van der Waals forces.