Seawater is fed into the system, passing through the condenser (1) and air-brine ejector (2). A small part of the seawater is used as feedwater for the evaporator. The air-brine ejector, driven by the seawater, evacuates both the excessive feed water and the chamber. A heating medium is fed into the evaporator. After approximately 5 minutes a vacuum of 90% is reached and evaporation of the feed water commences. The vapour flows through a demister (3) and is condensed in the condenser section. The distillate is pumped out of the unit.