In the title compound, C(21)H(21)N(5)O(2)·H(2)O, the seven-membered ring adopts a boat-shaped conformation with the methine C atom as the prow. In the crystal, the water mol-ecule links adjacent mol-ecules by O-H⋯O and O-H⋯N hydrogen bonds into a zigzag chain running along the c axis of the monoclinic cell.