Homemade Gravity Water Filter

In the 1800s, natural spring water was safe to drink, but in the 21st century, even remote mountain streams must be filtered. The destruction of our environment has become a consequence of progress. Today, every water source is potentially unsafe, so water filters and purifiers have become essential for good health. Since gravity filters are economical and effective, you might want to build one yourself.

Preparing the Clay

• Since clay (ceramic) filters can eliminate 99.9 percent of viruses and bacteria, while removing solids and improving taste, they're an ideal gravity filter medium. You'll need powdered clay, from a pottery producer, and sawdust, from a lumber mill, to make your clay.
  Use a sieve, made from window screen or mosquito netting, to sift the clay and sawdust into a uniform particle size. This will regulate the porosity of your finished product to insure a reasonable flow rate without undermining the filter's performance.
  Mix equal parts of clay and sawdust in a container, and add water till the clay is slightly moist and holds its shape when you squeeze it through your hands. You should knead the clay until you've removed any air pockets.

Making the Pot

• You'll need a two-piece flower pot press mold to give your clay the desired shape. Put the kneaded lump into the female half and insert the male section. Push the two halves together until they're 1/4 inch apart. Carefully separate the halves and remove the shaped clay. After you clean up the freshly molded pot, put it in a shaded place and let it air dry for a day.
  When a day has passed, transfer the pot to a kiln and slowly raise the temperature to 212 degrees F. This will give the trapped water a chance to escape without boiling and cracking the pot. When you reach 212 degrees, quickly increase the temperature to 1,650 degrees F. Hold this temperature for several hours to cook the pot, then let the kiln cool slowly for another two hours. Remove the pot when you can handle it with your bare hands.

Testing, Coating and Final Assembly

• When the pot has cooled to room temperature, soak it in water, then test it to see if the flow rate falls between 1 and 2 liters per hour. You can do this by filling it with half a liter of water and timing how long it takes to empty. If it passes the test, set it aside until it's completely dry.
  Add 2 ml of 32,000 ppm colloidal silver to 300 ml of purified water and immerse the dry pot until it's coated with this solution. Set it aside till it's dry, then put it in a plastic bucket with a spigot on the bottom.