The asymmetric unit of the title compound, C(3)H(5)N(2) (+)·C(6)H(2)N(3)O(7) (-)·C(3)H(4)N(2)·H(2)O or H(C(3)H(4)N(2))(2) (+)·C(6)H(2)N(3)O(7) (-)·H(2)O, contains a diimidazolium cationic unit, one picrate anion and one mol-ecule of water. In the crystal, the components are connected by N-H⋯O, N-H⋯N and O-H⋯O hydrogen bonds, forming a two-dimensional network parallel to (001). In addition, weak inter-molecular C-H⋯O hydrogen bonds lead to the formation of a three-dimensional network featuring R(5) (5)(19) rings.