To purify water, one of the ways that you can purify it is to take rocks, hot rocks, and grabbing them from the fire with your tongs, cleaning them off and then picking them up, and putting them in your water. So I clean them off first and then put them in the water. You don't have to clean them off. You can drink the charcoaly, but it's nicer if you clean them off a little bit. And if we look, we can start to see bubbles coming up in our water. One more should do it. Actually this is boiling right now. If you look in there, you'll see this it's boiling really pretty hard. So, this one will boil in a second as well. If you don't have access to a pot, you would make your own pot and you can boil water in it. And if you look right now, you can see there are little bubbles and this water's pretty close to boiled right now. Actually, now you can see bigger bubbles. So, I've got a few rocks left in the fire here which is what I want. I want to have a bunch of rocks so that I can reheat rocks basically. So this water's heating up really pretty well. And I might want to put newer, hot rocks in so I can get an older rock out. And this is where it pays to have a nice set of tongs to put a hotter rock in.