The origin of Earth's water is one of the most puzzling issues of solar system formation. The local environment of Earth during its early accretion was sufficiently hot to prevent hydration of planetesimals and protoplanets at 1 AU. That is, the Earth's nearby building blocks were likely devoid of water and water must have been delivered to Earth from farther distances. The late veneer scenario considers comets as the careers of water to the young and newly formed Earth. However, the measured value of D/H ratio in comets is approximately twice as its corresponding terrestrial value. Modern dynamical models of terrestrial planet formation suggest that, during its formation, water was delivered to Earth by planetesimals and planetary embryos, past roughly 2.5 AU.  However, this scenario is not consistent with Earth noble gas abundances. On the other hand, with routine discoveries of extrasolar planets, it is only a matter of time before additional terrestrial planets are also discovered. Whether any are suitable for life depends critically on the availability of water. If most of Earth's water was delivered from the asteroid belt or comets, what does this imply for water inventory for planets in the habitable zones of other stars? This talk will address these issues and review the current status of research in this area.