Desalination can be achieved though different techniques, such as distillation, freezing, instant evaporation or hydrate formation, but the method used most widely today is reverse osmosis.
Desalination by reverse osmosis, whether seawater or ground or brackish water, consists of pumping water at high pressure and passing it through nearly impermeable membranes that separate the water and the salt, obtaining to product waters: one that is discarded, with a high concentration of salt (brine), and the other with a low concentration of salt, which, when treated appropriately (remineralisation in the case of drinking water), is the water destined for the end use.
Prior to the reverse osmosis, different pre-treatments are required for the water depending on the quality of the raw water (sand filtration, nanofiltration, microfiltration, etc.) to avoid damaging the delicate osmosis membranes.