Filtration is a process of removing particulate and bacterial impurities which could not be removed in earlier processes, from water by passing it through a porous medium. It is an important stage in the purification of water.

Objects of Filtration

• To remove suspended, colloidal and other impurities which impart turbidity to water and untrapped by previous processes.
• To reduce bacterial load by about 90%.
• To produce sparkling and aesthetically attractive water.
• To reduce odour and colour imparted by fine colouring matter, by arresting them in filter media.
• To alter the chemical characteristics of water.