TL;DW: You only need the Sun to generate drinkable Water from the moisture in the air. They say It works in every environment (even in the desert).
It costs about 2000 $ and 500 $ installation, so 4500 $ for a 2 pannel array (as in the video).
But Dr. Ashok Gadil, Chair Professor of Safe Water and Sanitation, Environment Engineering, UC Berkleley says:
At the moment it would only be useful if you are on an island with no water supply and have a lot of money. It's not the best, cheapest and environment friendly solution to generating water. It would be better to harnes water from morning dew or to recycle used water.