Salt water purification

How much fresh water (in gallons) do you need on a daily basis? Is this water for general utility use and/or for drinking? Is the primary source ocean water or some other brackish source?

If the quantity is fairly low, (under 5 gallons per day) and you have good sun exposure, space availible, a clean source of water, a solar still may work. (distillation) They are a lot of work/maintenance and temperamental.

Chum lee