Fresh water supply on ships. Desalination
Rapid distillation of sea-water under reduced pressure can be used to provide fresh water on steamships. The reduction in pressure in the condenser is brought about by a vacuum pump very similar in principle to a laboratory filter pump, except that it works by a steam jet instead of a water jet. The water is heated by waste steam from the turbines.
Desalination (salt-removing) plants working on this principle can produce over 600 t of distilled water per day which is used not only to feed the boilers but also for all domestic uses on board. For the latter purpose a small quantity of a mixed salts solution is added to make it like naturally occurring water.