Desalination, desalinization, or desalinisation refers to any of several processes that remove some amount of salt and other minerals from saline water. More generally, desalination may also refer to the removal of salts and minerals, as in soil desalination.

Salt water is desalinated in order to produce fresh water that is suitable for human consumption or irrigation. One potential by-product of desalination is table salt. Desalination is used on many seagoing ships and submarines. Most of the modern interest in desalination is focused on developing cost-effective ways of providing fresh water for human use. Along with recycled wastewater, this is one of the few non-rainfall-dependent water sources.

Large-scale desalination typically uses large amounts of energy and specialized, expensive infrastructure, making it more expensive than fresh water from conventional sources such as rivers or groundwater.

Desalination is particularly relevant to countries like Australia which traditionally have relied on collecting rainfall behind dams to provide their drinking water supplies.

Menachem Elimelech is the Roberto C. Goizueta Professor of Environmental and Chemical Engineering and Chairman of the Chemical Engineering Department at Yale University. In 1998, he founded Yale's Environmental Engineering Program for which he continues to serve as director. Elimelech specializes in problems involving physicochemical, colloidal, and microbial processes in engineered and natural environmental systems.