Solar Filter

• 1). Dig a hole in the ground about 7 inches deep and wide. Line the hole with a piece of plastic tarp and place a large, flat rock in the center of the hole. Place a jar or canteen on top of the rock; it should be stable -- no tilting or moving on its own.
  
  
• 2). Pour your dirty water into the tarp-lined hole around the rock. The water can fill the hole up to the bottom of your canteen or jar, but it must not splash into the container. You don't want it to contaminate your filtered water.
  
  
• 3). Cover the hole by folding over a corner of your tarp and making it taut. Hold the tarp down around the edges of the hole with several large rocks. Place a final large rock in the center of the tarp, over your jar, creating a dip.
  
  
• 4). Let the filter warm in the sun for several hours. The heat evaporates the water, separating it from the contaminants. The filtered water then condenses against the underside of the tarp and drips into the jar.
  
  

Sand Filter

• 1). Cut the bottom from a plastic soda bottle with a knife. Fold a cotton handkerchief in half twice and place it inside the upside down bottle, over the opening to the mouth.
  
  
• 2). Break up some charcoal into fine gravel. Add about 1 inch of charcoal to your bottle on top of the handkerchief. Put 1 inch of sand on top of that, followed by another 1-inch layer of charcoal. Continue alternating sand and charcoal layers to the top of the bottle. This is your filter.
  
  
• 3). Position the bottle mouth over your canteen or jar. Pour the dirty water into the filter and let it drip into your canteen. It may look black; don't worry, this is only charcoal dust. It will not hurt you when you drink the water. Boil any water produced using the filter for about five minutes per cup of water.