Water from air?
Air humidity is a very promising source of clean water: immense quantities of water are contained in the air in the form of water vapor.
Even in dry places, such as the Sahara Desert, each km3 of air contains the equivalent amount of 3 000 000 liters of water, which corresponds to a river 1 000 m long, 3 m broad and 1 m deep!
All water on Earth comes from air which is recycled in a perpetual water circle. The air humidity is constantly renewed by winds from the oceans and, therefore, cannot be exhausted.