Bis(2-amino-4-methyl­pyridinium) terephthalate tetra­hydrate

In the crystal structure of the title salt, 2C(6)H(9)N(2) (+)·C(8)H(4)O(4) (2−)·4H(2)O, the terephthalate carboxyl­ate groups inter­acts with the 2-amino-4-methyl­pyridinium cations via a pair of N—H⋯O hydrogen bonds, forming an R (2) (2)(8) ring motif. The water mol­ecules form an R (6) (6)(12) ring motif through O—H⋯O hydrogen bonds and these motifs are fused, forming a supra­molecular chain along the c axis. The R (2) (2)(8) and R (6) (6)(12) ring motifs are connected via O—H⋯O hydrogen bonds. In addition, π–π stacking inter­actions are observed between the pyridinium rings [centroid–centroid distance = 3.522 (12) Å].