Heres a water filter we made in survival class while I was in the Army. I designed this in 1977 while stationed at Fort Huachuca, Arizona. It works great for removing the nasty taste from water you may find in the desert or dry areas. I'm not too sure it removes any pathogens. We used Iodine tablets for water purification. I hate the taste of the stuff so I made one of these up and it worked like a charm. If you don't know what a "C" ration is let me explain. They were tasty meals that came in small cans. There we several different menu's called "B" units. The cans contained things like ham and eggs, ham and lima beans ( we had a special name for these that I won't use in this blog), chicken and noodles, turkey loaf (very similar to turkey spam), etc. The little cans of peanut butter, jelly, and cheese spread looked like shoe polish. As a matter of fact, the contents TASTED like shoe polish! To be fair, some of the food was decent and we learned all kinds of different ways to spice it up and supplement it. In 1973 I received a box of "C" rats at Fort Dix, New Jersey during a training exercise. The date on the box was 1967. I ate them and they were good.
Since finding a "C" rat can is highly unlikely, a soda can or "Campbells Soup" size can will work fine. The "C" rat main meal can is halfway in size between a tomato paste can and a soup can.
The best way to view this drawing is to click on the image and it should enlarge or right click and save image to a file on your computer.
By the way, don't forget your "John Wayne"! Any Vets out there will know what this means.