Water in space: from interstellar clouds to planet-forming disks

Water is a key molecule in the physics and chemistry of regions in which new stars and planets are born. In the 'Water in Star-forming Regions with Herschel' (WISH) Key Program, we are obtaining a comprehensive set of gaseous water data toward a large sample of well-characterized protostars, covering a wide range of masses and luminosities -from the lowest to the highest mass protostars-, as well as evolutionary stages -from the earliest stages represented by pre-stellar cores to the late stages represented by the pre-main sequence stars surrounded only by disks.  The data elucidate the physical processes responsible for the warm gas, probe dynamical processes associated with forming stars and planets (outflow, infall, expansion), test basic gas-phase and gas-grain chemical processes, and reveal the water trail from clouds to planet-forming disks. New insight into the origin of the water in oceans on Earth comes from observations of deuterated water. Prospects for future ALMA observations will be discussed as well.