The title compound, C(12)H(10)N(4)·4H(2)O, was obtained from a room-temperature solution of o-phenyl-enediamine and copper acetate. In the crystal structure, there are significant π-π stacking inter-actions, with a centroid-centroid separation of 3.575 (2) Å. In addition, inter-molecular O-H⋯O, N-H⋯O, N-H⋯N and O-H⋯N hydrogen bonds link 2,3-diamino-phenazine mol-ecules and water mol-ecules, forming a three-dimensional framework.