Bis­(melaminium) sulfate dihydrate

The crystals of a new melaminium salt, bis(2,4,6-tri­amino-1,3,5-triazin-1-ium) sulfate dihydrate, 2C₃H₇N₆⁺·SO₄²⁻·2H₂O, are built up from monoprotonated melaminium(1+) residues, sulfate(2−) anions and water mol­ecules. The SO₄²⁻ ion has a slightly distorted tetrahedral geometry. The melaminium residues are interconnected by N—H⋯N hydrogen bonds, forming chains. The chains of melaminium residues develop a three-dimensional network through multiple donor–acceptor hydrogen-bond interactions with sulfate anions and water mol­ecules.