The title compound, C(5)H(3)F(3)N(2)O(2)·H(2)O, was prepared by the reaction of ethyl 4,4,4-trifluoro-3-oxobutano-ate with urea. In the crystal, the 6-(trifluoro-meth-yl)pyrimidine-2,4(1H,3H)-dione and water mol-ecules are linked by N-H⋯O and O-H⋯O hydrogen bonds. A ring dimer structure is formed by additional inter-molecular N-H⋯O hydrogen bonds.