An improved water desalination system is disclosed, in which contaminated water such as seawater or brackish water is preheated and fed into a primary pressure vessel through a distribution head. The seawater is distributed from the distribution head over a non-adherent surface such as a plurality of silicone chords hanging below a distribution tank or a cone- and cylindrical-shaped surface. The water is exposed to a high temperature steam environment in the chamber to cause at least a portion of the water in the contaminated water to evaporate, while the remaining concentrated salts from the contaminated water fall to the bottom of the chamber. A portion of the steam in the primary pressure vessel is withdrawn to be condensed into fresh water. The energy withdrawn with the steam extracted from the primary pressure vessel is made up by a supplemental energy apparatus, such as a steam generator.