We report herein the synthesis, crystallographic analysis and a study of the noncovalent interactions observed in the new 4′-substituted terpyridine-based derivative bis[4′-(isoquinolin-2-ium-4-yl)-2,2′:6′,2″-terpyridine-1,1″-diium] tris[tetrachloridozincate(II)] monohydrate, (C₂₄H₁₉N₄)₂[ZnCl₄]₃·H₂O or (ITPH₃)₂[ZnCl₄]₃·H₂O, where (ITPH₃)³⁺ is the triply protonated cation derived from 4′-(isoquinolin-4-yl)-2,2′:6′,2″-terpyridine (ITP) [Granifo et al. (2016). Acta Cryst. C72, 932-938]. The (ITPH₃)³⁺ cation presents a number of interesting similarities and differences compared with its neutral ITP relative, mainly in the role fulfilled in the packing arrangement by the profuse set of D–H⋯A [D (donor) = C, N or O; A (acceptor) = O or Cl], π–π and anion⋯π noncovalent interactions present. We discuss these interactions in two different complementary ways, viz. using a point-to-point approach in the light of Bader's theory of Atoms In Molecules (AIM), analyzing the individual significance of each interaction, and in a more ‘global’ analysis, making use of the Hirshfeld surfaces and the associated enrichment ratio (ER) approach, evaluating the surprisingly large co-operative effect of the superabundant weaker contacts.