chlorination

Too much chloride added to water will make the water smell bad.

As rainwater is acidic, lime is added to water in treatment works to make water slightly alkaline to avoid corrosion of water pipes.

Alum is added to water in treatment work in order to stick dust and sand together and then sink them to the bottom of the sedimentation tank.

Chorine is added to to kill micro organisms in water in the filtration tank of the water treatment work.

We can use chlorine to kill micro-organisms.Chlorine is a toxic chemical.It has a pungent smell.It is added to water and some local swimming pools for sterilization.