In the title Schiff base compound, C(12)H(11)BrN(4)O·H(2)O, the organic mol-ecule exists in an E configuration with respect to the C=N double bond. The pyrimidine ring is approximately planar, with a maximum deviation of 0.011 (2) Å, and forms a dihedral angle of 10.68 (8)° with the benzene ring. In the crystal, inter-molecular O-H⋯N, N-H⋯O and C-H⋯O hydrogen bonds link the mol-ecules into a two-dimensional network parallel to the ac plane.