What is Low-temperature thermal desalination?

Low-temperature thermal desalination is a desalination technique which takes advantage of the fact that water evaporates at lower temperatures at low pressures, even as low as ambient temperature. The system uses vacuum pumps to create a low pressure, low-temperature environment in which water evaporates even at a temperature gradient of 8 °C between two volumes of water. Cooling water is supplied from deep sea depths of as much as 600 metres. This cold water is pumped through coils to condense the evaporated water vapor. The resulting condensate is purified water.