As a chemical compound, a water molecule contains one oxygen and two hydrogen atoms that are connected by covalent bonds. Water is a liquid at standard ambient temperature and pressure, but it often co-exists across the known universe with its solid state, ice; and gaseous state, steam.
Water may be produced as a byproduct of star formation and it has been detected in interstellar clouds within the Milky Way Galaxy. Water is crucial to the existence of life on most other sentient species home planets, including Earth, Centauri Prime, Minbari and Narn. Earth's surface is two-thirds water.