Currently the desalination plants, each of which provides at least 100,000 litres of potable water everyday, are powered by diesel generator sets — there being no other source of power in the islands. LTTD exploits the difference in temperature (nearly 15°C) in ocean water at the surface and at depths of about 600 feet. This cold water condenses water at the surface, that is warmer but whose pressure has been lowered using vacuum pumps. Such de-pressurised water can evaporate even at ambient temperatures and this resulting vapour when condensed is free of salts and contaminants and fit to consume.