A makeshift water filter can be made by cutting the bottom off of a water or soda bottle, tying a piece of cloth to the opening and filling the bottle with a variety of materials starting with fine and working up to more course. Tying the bottle to a tree or post driven into the ground makes using it easier. Use the cut-off bottle bottom to scoop source water and pour it into the filter. Collect the water in a metal pot, pan or bottle so that it can be boiled for purification.