In the title compound, {[Zn(3)(C(9)H(3)O(6))(2)(C(12)H(12)N(2))(2)(H(2)O)(6)]·6H(2)O}(n), one Zn(II) atom, lying on an inversion center, is six-coordinated by two O atoms from two benzene-1,3,5-tricarboxyl-ate (btc) ligands and four water mol-ecules in a distorted octa-hedral geometry. The other Zn(II) atom is five-coordinated by two N atoms from a 5,5'-dimethyl-2,2'-bipyridine (dmbpy) ligand, two O atoms from two btc ligands and one water mol-ecule in a distorted trigonal-bipyramidal geometry. The compound features a one-dimensional ladder structure, with windows of ca 10.245 (1) × 15.446 (2) Å. The ladders are linked together by inter-molecular O-H⋯O hydrogen bonds and π-π inter-actions between the benzene rings and between the pyridine rings [centroid-to-centroid distances 3.858 (2) and 3.911 (3) Å, respectively] to form a three-dimensional supra-molecular structure. One of the lattice water molecules is disordered over two positions in a 0.592:0.408 ratio.