Bis(3-amino-propan-1-aminium) naphthalene-1,5-disulfonate dihydrate.

In the title hydrated salt, 2C(3)H(11)N(2) (+)·C(10)H(6)O(6)S(2) (2-)·2H(2)O, the anion lies on a center of inversion; its sulfonate -SO(3) group features one S-O bond that is longer than the other two. The O atom of this longer bond is the hydrogen-bond acceptor to the amino H atom of one cation and the ammonium H atom of another cation. In the crystal, N-H⋯O and O-H⋯O hydrogen bonds link the cations, anions and water mol-ecules into a three-dimensional network.