Water Out Of The Air?

My brother came up with an interesting idea when I saw him today. We were talking about purified water (RO/DI) for reefs, and he said "Why not just take it from the air, like out of a dehumidifier?". If water is pure in the air, why not? I'm sure there are flaws in this idea. My thoughts for flaws on this were that dehumidifiers put other things in the water that you don't want, my conception of the pureness of water vapor is off, or dehumidifiers don't just take water out of the air. Just thought I'd mention this as it intrigued me.

 

I did further research and figured out all of the reasons that this doesn't work, so... never mind.

 

Too many metals in a dehumidifier that may end up in the water.

 

There is a company that is based in the Dominican that take drinking water from the air because it's so humid there. Really cool idea.