Hamaker constants of systems involving liquid water are evaluated, within the full Lifshitz theory, by means of a recently proposed model of the dielectric function of this substance [Dingfelder et al., Radiat. Phys. Chem.53, 1 (1998)], which has been extended in the present work by including terms corresponding to infrared excitations and microwave relaxation. An important feature of the complete model is that, besides a good fit to experimental data, it satisfies the physical constraint provided by the f sum rule. For symmetrical systems interacting across water, calculated Hamaker constants are generally in good agreement with results obtained using the Ninham–Parsegian representation with the Roth and Lenhoff parameters for water.