In the title compound, C(8)H(9)N(3)S·H(2)O, intra-molecular N-H⋯N hydrogen bonding contributes to the mol-ecular conformation. Water mol-ecules are involved in inter-molecular N-H⋯O and O-H⋯S hydrogen bonds, which link the mol-ecules into ribbons extended along the a axis. Weak inter-molecular N-H⋯S hydrogen bonds link these ribbons into layers parallel to the ab plane with the phenyl rings pointing up and down.