How is water treated?

After collecting water from a natural waterbody, the raw water undergoes sedimentation. During sedimentation, some particles spontaneously settle down. For particles slow to settle, chemicals (coagulants) are added to the water. This leads to the formation of larger particles that settle rapidly.

As fine suspended particles hold bacteria and viruses to their surface, these processes can remove up to 99 per cent of the bacteria and viruses. In the next step, filtration removes even smaller particles when the water passes through a bed of fine particles, generally sand. Membrane filtration is also used where water is filtered through tiny holes (pores) in a membrane rather than a bed of sand.

Then the water is disinfected using chlorine and stored and supplied through a public distribution system.

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