Question

how water purification system in water works

Answer 1

The treatment piece of this process is called the water-treatment process. The water treatment process involves four steps, in this order: coagulation, sedimentation, filtration, and disinfection.
Coagulation:In water treatment, coagulation flocculation involves the addition of polymers that clump the small, destabilized particles together into larger aggregate so that they can be more easily separated from the water. 
Sedimentation: Sedimentation is a physical water treatment process using gravity to remove suspended solids from water.
Filtration:Filtration is any of various mechanical, physical or biological operations that separate solids from fluids by adding a medium through which only the fluid can pass. The fluid that passes through is called the filtrate.
Disinfection: Water disinfection means the removal, deactivation or killing of pathogenic microorganisms. ... When microorganisms are not removed from drinking water, drinking water usage will cause people to fall ill. Sterilization is a process related to disinfection.

Answer 2

Answer:

1. Sedimentation:

Water pumped from the source (river, lake or dam) is allowed to stand in large tanks, called settling tanks, for a few hours. Mud, sand and other suspended particles settle down. The addition of a small quantity of potash alum (K2SO4 . A12(SO4)3 . 24H2O) helps the suspended particles to settle down quickly. The solid that settles at the bottom of the tank is called sediment. That is why these tanks are also called sedimentation tanks. The water over the sediment layer is more or less clean.

2. Filtration:

The water from the sedimentation tank is filtered through layers of sand and gravel. Filtration is also done through activated charcoal, which affords better-quality water. Activated charcoal is a special type of charcoal made by heating ordinary charcoal in vacuum. This charcoal holds the impurities strongly.

3. Chlorination:

The filtered water is then treated with chlorine gas, which kills germs. You can see for yourself that alum helps the suspended particles of water to settle down quickly. Take two similar glasses containing equal volumes of muddy water and label them A and B. (You can prepare muddy water by mixing a teaspoonful of mud from your garden with the water in the glass.)

Crush a small crystal of alum (which you can obtain from a store) between the folds of a paper and add it to A. Stir the water in the two glasses and allow them to stand side by side. Within a short while, you will find that the mud has settled down with clear water above it in glass A, but the water is still not clear in glass b