Everyone knows that boiling clear water will sterilize it and make it safe for drinking. If the water is dirty/cloudy you need to filter the water first. Pouring the water through a folded up t-shirt works well. You want to get your water as clear as possible.
The questions is, how do you boil water if you don’t have a metal cup or pan? This video answers that question whilst also teaching you two great bush-craft/survival techniques: how to boil water with hot rocks and how to make a cup/bowl from willow bark. Combine the two techniques and you can boil water in the wild.