Quantum effects in water are investigated by implementing the Feynman-Hibbs effective potential in a molecular-dynamics code. The reference potential chosen for water is a new central force model related to the one proposed in the 1970s by Lemberg and Stillinger [J. Chem. Phys. 62, 1677 (1975)]. The evolution of the thermodynamics, the structure, the diffusivity, and the dynamics in light and heavy water is investigated over a large range of temperature and is compared with experimental data and with classical simulations as well. It is found that quantum effects are significant near ambient conditions and vanish with increasing temperature less drastically than generally assumed. The most affected quantity is the self-diffusion coefficient for which is predicted a marked increase of the isotopic ratio (D-H2O/D-D2O) in going into the supercooled region. The accuracy of the results and the very low cost in computer time make the Feynman-Hibbs approach a valuable procedure to rapidly estimate the order of magnitude of the quantum contributions to intermolecular propel-ties of water.