Abstract
The title compound, K(+)·C(6)H(9)N(4)O(4) (-)·H(2)O, crystallizes with the K atoms located on special positions related by pseudocentres of symmetry. Each K atom is coordinated by six O-atom donors. The N and water H atoms are involved in inter- and intra-molecular N-H⋯O, N-H⋯N and O-H⋯O hydrogen bonding. The data indicate inversion twinning.