In the title compound, [Na(C₁₁H₁₁ClN₃O₃)(H₂O)](n), there are two independent Na(I) ions, one of which lies on an inversion center and is coordinated in a slightly distorted octa-hedral environment. The other Na(I) ion lies on a twofold rotation axis and is cooordinated in a slightly distorted trigonal-bipyramidal coordination environment. In the organic ligand, the imidazolidine ring adopts a half-chair conformation. The Na(I) ions bridge organic ligands and water mol-ecules, forming a two-dimensional structure parallel to (100). There are inter-molecular O-H⋯O and weak C-H⋯O hydrogen bonds within the two-dimensional structure.