Desalination, removal of dissolved salts from seawater and in some cases from the brackish (slightly salty) waters of inland seas, highly mineralized groundwaters (e.g., geothermal brines), and municipal wastewaters. This process renders such otherwise unusable waters fit for human consumption, irrigation, industrial applications, and various other purposes.
Existing desalination technology requires a substantial amount of energy, usually in the form of fossil fuels, and so the process is expensive. For this reason it is generally used only where sources of fresh water are not economically available.