|Written by mamajoe|
Cut the bottom off of the two liter bottle. Cut a hole in the lid and insert the straw into the hole so the filtered water will flow out of the straw.
Insert the cotton batting at the bottom of the bottle. If you have charcoal granules, layer those next. The next layer is fine grain sand followed by larger grain sand. After the sand layers, add the gravel layers. Start with the fine grain gravel followed by the larger grain gravel. Alternate these layers until you reach the top of the bottle. Top the layers off with the coffee filter.
Once you have everything in place, pour the water through the coffee filter. The water will work through the different layers to remove the impurities. The cotton batting at the bottom works as the final layer to catch particles from the sediment. The water will flow out of the straw and into the cup.