The Fontus bottles use solar power to pull in moisture from the air, cool it and fill them up with water. In high humidity conditions you can have half a quart of water in an hour (less in dryer conditions). Of course, you will want the air around the bottle to be pretty free of contaminants.
More on the science of Airo and Ryde (same type bottle for cyclists) by Fontus.
Visit the Fontus website to donate to their IndieGogo campaign and get a discount on the bottle when it comes out later this year.