Purification of Water

Contaminated or non-potable water can be treated to turn it into potable or drinking water.

1. Decantation

By decantation, insoluble impurities can be removed. Decantation is the process of separation of solid from the liquid by allowing the former to settle down and pouring off the latter. Water is kept in a vessel for some time.

The suspended insoluble impurities settle down at the bottom. Clean water can now be carefully poured into another clean vessel without disturbing the settled impurities which are left behind. But, this water has to be made fit for drinking through further treatment.

2. Filtration

By filtration, the insoluble impurities can be removed. It is a more effective method than decantation and can remove even very fine particles of insoluble impurities. A piece of clean and very fine cloth can be used as a cheap and easily available filter. When water is poured through it, the insoluble impurities are stopped by the filter and clean water passes through it.

Commercially available water filters use "candles" made of porous material. Pure water passes through it leaving the impurities on its outer surface. These candles must be cleaned and washed periodically to maintain their effectiveness.

3. Boiling

By boiling, bacteria and other germs in the water get killed. When boiled water is allowed to cool, heavy impurities collect at the bottom and dissolved salts form a thin layer on the surface called scum. Now if we filter the water, it becomes safe for drinking.

4. Chlorine Treatment

By chlorine treatment small living organisms and bacteria are killed. If required, treated water may be filtered to remove insoluble impurities.