I expeimented with an idea about sea water when I used to kayak around the islands in the Miami bay.
A tea kettle can be rigged with a length of spiral copper tubing (like a moonshine still), so that the steam from the boiling water condenses in the tubing.
My rules for this experiment was that I had to use the fire from dried, burning seaweed, as seaweed is, essentially, limitless if one knows how to swim and snorkel.
Seawed does burn if it's dried out carefully, but not as efficiently as wood or coal. It also smells pretty bad.
I was--however--able to make about a gallon and a half of pure water every day with two large tea kettles.
Just keep in mind that this procedure is very labor intensive, needs constant tending, and that salt residue needs to be regularly cleaned out of the tea kettles.
Also, certain materials (like a cast-iron tea kettle) will rust much quicker because of the salt water. It works and is practical . . . but barely.
Dangerous Laboratories
Welcome to Dangerous Laboratories! › ...
Teakettle Still!
I would use this method in conjunction with other methods at the same time. A transpiration still can be set up with a plastic bag, twine, a pebble, and live vegetation. A solar still requires a shovel, a large plastic sheet, and some aquarium tubing.
This is a transpiration still:
Below is a lifeboat solar still available for less than $250.00.
Below is a solar still from a plastic dropcloth:
I hope this helps.
Let me know if I can answer any questions.