A new seawater desalination method, Nord-Aqua Vacuum Evaporation, which utilizes waste heat at a very low temperature, has been developed. The requisite vacuum is obtained by a barometric column and siphon, and the dissolved air is removed from the vacuum by water flows. According to test results from a pilot plant, the process is operable if the waste heat exists at a temperature 7 K higher than ambient. The pumping energy that is then required is 38 kJ/kg, or 1.5% of the heat of vaporization of water. Calculations reveal that the method is considerably superior economically to conventional distilling methods.