If you ever are in an emergency setting where your drinking water is questionable check this out. A free way to distill water for purification. While you couldn’t distill gallons you just might survive since you could have clean water to drink. 
While you can buy distillers to have on hand for emergencies and they would allow you to distill about a liter per hour of water but this would at least provide a little for drinking. Desert Sun 02 shows us how to distill water easily in this video.
