The structure of the title compound, [Cu2Cl2(C4H13N3)2(H2O)]Cl2, at 180 K is described in space group P21/n with a unit-cell volume twice that reported previously for the structure at 293 K [Willett (2001[Willett, R. D. (2001). Acta Cryst. E57, m605-m606.]). Acta Cryst. E57, m605-m606]. In the smaller unit cell, in space group P21/m, the complex has imposed mirror symmetry and unusually elongated displacement ellipsoids. At 180 K, refinement in the larger unit cell with no imposed symmetry resolves this issue. With room-temperature data collected from the same crystal, however, refinement using the larger unit cell gives no significant improvement, and the previously reported structure is considered to be most appropriate.