2-Amino-4-methyl­pyridinium 3-carb­oxy-4-hy­droxy­benzene­sulfonate monohydrate

In the crystal structure of the title salt, C(6)H(9)N(2) (+)·C(7)H(5)O(6)S(−)·H(2)O, the water mol­ecule acts as an acceptor of bifurcated N—H⋯O hydrogen bonds from the pyridinium H atom and one H atom of the 2-amino group, forming an R (2) (1)(6) ring. The 3-carb­oxy-4-hy­droxy­benzene­sulfonate anions self-assemble via O—H⋯O hydrogen bonds, leading to supra­molecular chains along the a axis. These chains and R (2) (1)(6) motifs are linked via O—H⋯O, N—H⋯O and C—H⋯O hydrogen bonds, forming a layer parallel to the ac plane. There is also an intra­molecular O—H⋯O hydrogen bond in the 3-carb­oxy-4-hy­droxy­benzene­sulfonate anion, generating an S(6) ring motif.