Ceramic water filters are filters created with the intention of filtering chlorine and other contaminants out of water sources to provide clean drinking water. They are usually comprised of a dry clay-sawdust mixture to create a porous clay ceramic.
This type of filter is a common solution to the problem of obtaining clean water in many parts of the world, especially rural parts of developing nations. It is a fairly simple process that involves only materials that are available in most parts of the world.
Note that this filter can only filter particles and color out of the water. It cannot filter bacteria or viruses. Water filtered through this filter is not fit for immediate drinking, and it is required that the water be boiled before being consumed by humans.
Why Clay
Many advocate a hands on approach - intervention provided by the WHO or other organizations - however, this is problematic for a few reasons. While direct distribution of clean water is effective, the problem lies in the transport process. Pipelines are problematic because users tap them illegally, and truck deliveries are rejected as unsanitary and dependent on unreliable sources of water. Additionally, cities in developing countries are unable to pay the high cost of water treatment plants.
Clay solves most, if not all, of these problems. They are simple to make and highly effective sources of cleaner water for areas in the world suffering from dirty water. The cost is cheap and provides individuals ways to create their own water.