1-(3-Carboxyl­atophen­yl)-4,4′-bipyridin-1-ium dihydrate

In the crystal structure of the title compound, C₁₇H₁₂N₂O₂·2H₂O, the carboxyl­ate group is linked via O—H...O hydrogen bonds to two water mol­ecules. The crystal packing is best described as parallel layers (viewed along the a axis) of viologen and water mol­ecules associated via O—H...O hydrogen bonds and π–π inter­actions, with a centroid–centroid separation of 3.8276 (9) Å.