There may come a time in a survival situation when you don’t have access to clean water, you’ve run out of water filtration tablets, and you don’t have any other means of ensuring that your drinking water is safe. Even clear, running water can be filled with bacteria that can quickly make you extremely sick, so it’s never a good idea to just guess. Here’s an easy way to create a water filtration system with what you can find in the wild, that will remove as much harmful bacteria as possible.
Begin with a water bottle, sports drink bottle, or some other kind of bottle that has a smaller opening on one end. Cut open the larger end, so that your water bottle has no bottom. Put the cap on the smaller opening, and make a small hole in the center of the cap. If you don’t have the cap, secure a piece of thin cloth or a paper towel over the end, and don’t cut a hole.
The first layer that should be inserted through the large opening and lined securely at the narrower end is a coffee filter, a piece of thin fabric, or some cotton balls. In an emergency situation, tearing a piece off your clothing should work. Then begin filling the bottle with about one to two inches of each of these layers: fine sand (or crushed charcoal), small gravel, larger rocks.
Hold the bottle over a container to catch the clean water, and slowly pour your dirty water into the large opening. To ensure that this newly filtered water is perfectly safe, you can boil it to get out the last of the bacteria. This isn’t a fast method of filtering a lot of water, but it will work great in a pinch.