Liquid-vapor, solid-vapor, and solid-liquid-vapor equilibria are studied for the pure substance water, using modern equipment that includes specially fabricated glass cells. Samples are evaporatively frozen initially, during which they typically supercool to -5 to -10 [degrees]C before spontaneously freezing. Vacuum pumping lowers the temperature to [approximately]-20 [degrees]C, and temperature and pressure are recorded on warm-up, first for sublimation, then vaporization, with a pronounced halt at the triple point. Analysis of the data by the integrated Clausius-Clapeyron equation typically yields [delta][subscript sub]H[subscript m] and [delta][subscript vap]H[subscript m] values within [approximately]2% (1 kJ/mol) of literature, from which [delta][subscript fus]H[subscript m] can also be estimated with fair precision. The experiment is designed for the undergraduate physical chemistry teaching laboratory; aspects of it are also appropriate for demonstrations in general and physical chemistry courses. (Contains 5 figures.)