The asymmetric unit of the title hydrated salt, C22H25N2 (+)·C6H4ClO3S(-)·H2O, comprises two 2-[4-(di-ethyl-amino)-styr-yl]-1-methyl-quinolin-1-ium cations, two 4-chloro-benzene-sul-fon-ate anions and two solvent water mol-ecules. One ethyl group of both cations displays disorder over two positions in a 0.659 (2):0.341 (2) ratio in one mol-ecule and in a 0.501 (2):0.499 (2) ratio in the other. The sulfonate group of one anion is also disordered over two positions in a 0.893 (7):0.107 (7) ratio. The dihedral angle between the mean plane of the quinolinium ring system and that of benzene ring is 10.57 (18)° in one cation and 14.4 (2)° in the other. In the crystal, cations, anions and water mol-ecules are linked into chains along the [010] direction by O-H⋯Osulfonate hydrogen bonds, together with weak C-H⋯Osulfonate and C-H⋯Cl inter-actions. The cations are stacked by π-π inter-actions, with centroid-centroid distances in the range 3.675 (2)-4.162 (3) Å.