similar to this have been around forever. Lots of life rafts had something similar to this. Makes a liter or two a day in decent weather
There is also something that looks like a beach ball you use to be able to buy. When you needed to use it you simply blew it up and put sea water
in the bottom. The ocean water
keeps the lower part cool and the clear plastic in the sun heats up the sea water which then condenses and drips into a container. No worries about mold
because you drink the water instantly.