i have to design a device that can purify seawater using only solar energy i have just one idea but still not sure it would work the idea is to buy a plastic bucket and a long cup or long and smaller bucket. then i put the long and smaller bucket into the big plastic bucket right in the middle. than i pour the sea water into the big bucket so it surrounds the small bucket. after that i cover the big bucket with glad wrap put it in the sun. i get a pebble (rock) and place it in the middle of the glad wrap. than the water that forms on the glad warp will all gather in the center and eventually fall into the smaller bucket.. the PROBLEM IS the water formed in the smaller bucket would vapourise too any ideas that could help me ?