In the title hydrated salt, C₁₅H₁₆NO₂⁺·C₆H₄BrO₃S⁻·H₂O, the cation exists in anEconformation with respect to the ethenyl bond and is almost planar, with a dihedral angle of 2.62 (12)° between the planes of the pyridinium and benzene rings. The methoxy substituent deviates slightly from the plane of its attached benzene ring [C_methyl—O—C—C torsion angle = −11.6 (6)°]. In the crystal, the cations, anion and water molecules are linked together into chains along [010] by O—H...O hydrogen bonds and weak C—H...O interactions. There is a short Br...O contact [3.029 (2) Å]. The crystal structure also features C—H...π interactions involving the benzene ring of the anion.