Abstract: A de-salinator 10 for brackish- or salt-water has a heat insulating shell 11 closed by end plates 12. A heat exchanger 22 in the bottom of the chamber 13 is heated by engine coolant from a marine engine 27, while a pair of condensor coils 19, connected to manifolds 33, 34, use sea water to cool the fresh water vapour which is drawn off by outlets 21. The engine driven pump 37 which draws the water through the condensor coils 19 operates an eductor 36 which generates a partial vacuum in the chamber 13, drawing off brine from the bottom of the chamber and any excess water in the chamber. The level of water in the chamber 13 is maintained by drawing off a portion of the heated water passing through the condensor tubes 19. The condensate is drawn from the outlets 21 via an eductor 46 which is driven by a suction pump 45 connected to the fresh water tank 47.