As most people know water is - if not THE most important survival component - certainly in the top two. If you are in a freezing environment shelter would be number one, or adrift in the ocean a boat would be number one...etc. If you fell through ice into a frozen lake - heat would be number one. You get my point. So there are instances where the lack of water is not your primary concern. But that is rare and is not the point here.
Many people believe that they must purchase an expensive commercial water filter in order to have a safe reliable water supply. Actually just the opposite is true. Commercial water filtration units are most often only serviced with their particular brand of filter element. What is really needed, is a unit which uses renewable, easily found or created filter media instead of filter cartridges.
When I went through SERE training in the military we learned, and practiced, fashioning survival water filters from all sorts of things, lengths of bamboo, socks, pipes, the list goes on. But the primary components of water filtration do not change.
First you need a container to direct and force the water through a mechanical filter element. The filter element can be many things and we will get to that shortly. Next you need a finer mesh or grade of filter element to eliminate fine suspended solids, after that a layer of charcoal to eliminate bad tastes and odors followed up by a final layer of small gravel to catch charcoal sediments. The vessel you use could be a simple bucket as show here:
Or you could get a 4" or 6" diameter PVC Pipe with a hose style end cap on it to do the same thing.
There are a few fine points to remember.
You can use any washed sand, gravel or charcoal. But if you gather sand from a creek or stream bed, or lakeshore, or any wet place - be sure to boil or dry cook it for at least 20 minutes to kill any pathogens which may be living in the interstitial spaces.
Charcoal should be crushed to a fine, somewhat regular consistency of pieces which should be around the size of pea's. Then the charcoal should be rinsed to remove the initial charcoal dust.
You also may want to save your excess charcoal - Activated Charcoal has been used effectively in the healing arts for centuries. Doctors still use it today as a healing agent, an antidote for poisons, and an effective treatment for indigestion and gas. Modern Industry also relies on Charcoal to deodorize, decolorize and purity solutions. Charcoal can do these varied tasks because of its amazing ability to attract other substances to its surface and hold them there. This is called adsorption. Charcoal can adsorb thousands of times its own weight in gases, heavy metals, poisons, and other chemicals, thus making them ineffective or harmless.
