Hydrogen bonding in 1-carbamoylguanidinium methylphosphonate monohydrate

The title compound, C(2)H(7)N(4)O(+).CH(4)O(3)P(-).H(2)O, crystallized with one carbamoylguanidinium cation, one methylphosphonate anion and one water molecule in the asymmetric unit. All H atoms of the carbamoylguanidinium ion are involved in a hydrogen-bonded network. The CH(3)PO(2)(OH) anions, together with the water molecules, build O-H...O hydrogen-bonded ribbons around a 2(1) screw axis parallel to the b axis. Neighbouring ribbons are not directly connected via hydrogen bonding. The carbamoylguanidinium cations are linked to these ribbons by N-H...O bridges and build a slightly buckled layer structure, the interlayer distance being b/2.