In the title compound, C(21)H(17)N(3)O(4)·H(2)O, the coumarin ring system is almost planar (r.m.s. deviation = 0.002 Å) and makes dihedral angles of 1.50 (7) and 57.75 (7)° with the pyrazole and phenyl rings, respectively. The dihedral angle between the pyrazole and phenyl rings is 56.60 (9)°. The pyrazole ring adopts a twisted comformation. The mol-ecular conformation is stabilized by intra-molecular N-H⋯O and C-H⋯O hydrogen bonds, both of which form S(6) ring motifs. In the crystal, each water mol-ecule is linked to its adjacent organic mol-ecule via pairs of O-H⋯O hydrogen bonds. The packing is further consolidated by pairs of inter-molecular C-H⋯O hydrogen bonds, which link the mol-ecules into dimers; the dimers are stacked along the b axis.