The title compound, [Zn(S2O3)(C18H12N6)(H2O)].0.5H2O, contains two almost identical independent monomeric moieties composed of an octahedral Zn centre coordinated by a tridentate 2,4,6-tri-2-pyridyl-1,3,5-triazine (tpt) ligand, one aqua ligand and an O,S-chelating thiosulfate anion. The structure is stabilized by a solvent water molecule. Multiple strong hydrogen bonds with additional weaker pi-pi interactions between tpt groups define a multiple column spatial organization.