Water filtration is a process which involves running water or forcing water under pressure through a filter material. There are many different types of filter materials; the materials are designed to remove particulates, metals as well as microbial pathogens. Filters are produced in a host of sizes, anything from small filters which are employed on household water faucets all the way to huge filter sheets which are employed in municipal Florida water treatment plants. Regardless of the size and material they are designed to filter out, they all are basically the same and operate under a common principle.
What is called the “media” is the material that actually captures and collects contaminates that are found in water, the media is the primary component of any filtration system. In large systems the media is often sand which is sometimes mixed with coal. Small systems which are in common use around the home commonly employ granular activated carbon. Granular activated carbon is a carbon material that has be subjected to a unique process which increases the surface area, hence its ability to take on more contaminates. If the problem is a high iron content, manganese greensand is the media of choice, for swimming pools diatomaceous earth is a popular material.
Small filters found in domestic installations normally consist of a single filter material, larger systems often are layered. Many large Florida water treatment filters are sand which is layered on top of gravel, these layers are then topped off with anthracite coal which is a fine grained layer. Water enters the top, it flows slowly through the fine upper layers, rapidly flowing through the gravel layer and then moving to the next destination.
To the naked eye the only movement is water flowing through the filter but there are other processes taking place which remove the various contaminates from the water. Those contaminates that are too large to move through the filter are removed with a sieve, the particles of the filter media absorb contaminates such as minerals and metals. The term absorption is used to indicate that contaminates actually attach to the filter material surface. Other filters break down contaminates biologically, the water flows through a layer of microorganisms which breaks down and consumes harmful bacteria that may be in the water.