In the Water Treatment system as well as sewage treatment system Slow sand filter is the large-scale water filtration methods. Slow Sand media water treatment filter is very old type water filtration but very effective water treatment system. In the slow sand filter, water entering first through about 32 -36 inches of sand, then through a multi size layer of gravel (This layer is known as schmutzdecke, which is German for “dirty skin.”) before entering the under-drain. The multi sized layer (schmutzdecke break down and removes organic particles from the water through the mechanism of biological action, adsorption and straining methods. The absorption of biological microorganism in sand filter media should be reformed by the backwash with water.