In the title compound, C13H12ClN3·H2O, the organic molecule is almost planar, with a dihedral angle of 3.22 (10)° between the benzene and pyridine rings. The crystal structure is stabilized by O—H⋯N and C—H⋯O hydrogen bonding and π–π stacking interactions [centroid–centroid distances = 3.630 (1) and 3.701 (1) Å].