take a glass of water and put some fruit like strawberries in the water and when it go's to the bottom it is ready to drink.
Use the tap.
You get some water and pour some salt in it. but u wont have plankton or any thing ales u get in the seas
It'd be a heck of a lot easier (and probably cheaper) to just buy it... but if you want to make it, you just need to boil water and condense and collect the steam somewhere else. It is the condensing...
Beavers