The organic mol-ecule in the title hydrate, C(17)H(14)ClN(3)O·H(2)O, has a small but significant twist from planarity, as seen in the dihedral angle of 12.10 (17)° between the quinoline and benzene rings. The conformation about the C=N bond is E. Chains along the b axis are formed in the crystal structure aided by water-quinoline O-H⋯N (× 2) and hydrazone-water N-H⋯O hydrogen bonds. Layers of these chains stack along the a axis via C-H⋯π and π-π inter-actions [ring centroid-ring centroid distance = 3.674 (2) Å]. C-H⋯O inter-actions are also present.