You can cover vegetation with plastic. The moisture that plants lose condenses on the plastic and provides drinking water. Make sure you can catch the drops at the lowest point of the plastic. You can bind a bag around a bunch of leaves or lay plants in a pit with foil stretched over it. A stone in the middle of the film makes this point the lowest. So, below this you put your cup. Around the cup, anything containing liquid is useful: leaves, green waste, moist soil, algae,.... Distillation is the only way to make urine or sea water drinkable.


On a small scale it’s also possible. Place a cup in the middle of a bowl. Pour wastewater on the bottom of the bowl. Fix a plastic wrap over the bowl and put a stone in the middle to make a dripping point. (Or use an egg cup and fill it regularly with cool water to get a better condensation effect. Or take an inverted metal lid with similar shape.) The scale or boiler can be heated on the stove. This is a variation on the way in which e.g. during WW II clandestine alcohol distillation from homebrew was made, without having suspect attributes in-house.

Is seawater drinkable
Seawater contains much salt. That makes you thirsty and dries the body cells. By drinking seawater chances to survive diminish rapidly.