How is seawater desalinated to produce drinking water?

Seawater is desalinated to produce drinking water primarily through two categories of technology: thermal processes and membrane processes.1

Thermal Processes

These methods involve heat transfer and phase changes to separate water from salt.1
* Multistage Flash Distillation: Seawater is heated and passed through a series of closed tanks at progressively lower pressures. This causes the water to "flash" into vapour, which is then condensed into fresh water.1
* Solar Humidification: A simple method where sunlight vaporizes salt water under a transparent cover; the vapour condenses on the underside of the cover and is collected.1
* Freeze-Thaw: This process relies on the fact that ice crystals formed from salt water contain no salt. However, it is often inefficient because fresh water is required to wash away brine trapped between the crystals.1

Membrane Processes

These methods use semipermeable materials to filter out dissolved salts.1
* Reverse Osmosis: The most widely used method, where salt water is forced against a semipermeable membrane under high pressure. Fresh water passes through the membrane, while mineral salts are left behind.12
* Electrodialysis: This process uses electrical potential to drive salt ions through specialized membranes, leaving fresh water behind.1