1,4-Bis(carboxymethyl)piperazine-1,4-diium bis(dihydrogen phosphate) dihydrate

In the title salt, C8H16N2O42+·2H2PO4−·2H2O, the piperazine ring is located around an inversion center and adopts a chair conformation. The dihydrogen phosphate anions and free water molecules are linked via O—H...O hydrogen bonds into two-dimensional hydrogen-bonding layers, which are further connected through O—H...O and N—H...O hydrogen bonds involving the protonated piperazine into a three-dimensional supramolecular network.