Bis(2-amino-5-bromo­pyridinium) fumarate dihydrate

In the title compound, 2C(5)H(6)BrN(2) (+)·C(4)H(2)O(4) (2−)·2H(2)O, the complete fumarate dianion is generated by crystallographic inversion symmetry. The cation is approximately planar, with a maximum deviation of 0.036 (1) Å. In the anion, the carboxyl­ate group is twisted slightly away from the attached plane; the dihedral angle between carboxyl­ate and (E)-but-2-ene planes is 6.11 (14)°. In the crystal, the carboxyl­ate O atoms form bifurcated (N—H⋯O and C—H⋯O) and N—H⋯O hydrogen bonds with the cations. The crystal packing is stabilized by R (2) (2)(8) ring motifs which are generated by pairs of N—H⋯O hydrogen bonds. The crystal structure is further consolidated by water mol­ecules via O(water)—H⋯O and N—H⋯O(water) hydrogen bonds. The components are linked by these inter­actions into three-dimensional network.