An article regarding research by Monash University into producing clean water using solar energy.
Another article regarding desalination using heat instead of electricity.
When we were younger and did a survival course (and no, I am not a doomsday prepper), a part of the course showed how ro make drinking water from very saline and dirty river/ground /ocean water.
It involved a bucket (prerferably dark in colour), clear plastic bag and a wet towel/cloth. The bucket water heats up through active sunlight, the bag containing the bucket gets hot and humid (air at saturation) and the damp cloth placed strategically on the outside of the bag is used to condense the water allowing it to flow to a corner of the bag…delivering clean drinking water provided one is careful.
I wonder if it is old things becoming new again?
No, just ionic magic and FO (forward osmosis).
Not that complicated, and relies on temperature differential rather than pressure and high levels of electrical power required for high capacity RO plants.