Watermakers are clever, but the problem is that they lull us into expecting lots of fresh water on tap. When they fail in mid-ocean, a sailor is in trouble unless he has backed them up by carrying at least twice the volume needed for his most pessimistic estimate of the passage time. On the whole I prefer to carry the water in every available corner of the boat and do without the watermaker.
The clever part seems to be that modern ones can recover the high pressure that must be generated and use this pressure when released to pressurise more water. This reduces energy required to run the system.
A bit of a red herring but this link relates to 3 plants here in West Oz each capable of producing 50 billion litres. The video claims that the energy required over one year is similar to that of running a refrigerator. http://www.watercorporation.com.au/d/desalination.cfm
I believe most war ships now rely on desalination RO for fresh water. good luck olewill