What are the steps in treating fresh water?

Raw water contains dissolved ions, microorganisms, pollutants and insoluble materials (e.g. sand and stones).

• Sedimentation: Large, insoluble particles to settle to the bottom. The cleaner water at the top is used for the next stage.
• Filtration: The it trickles through layers of sand and gravel which removes smaller insoluble particles.
• Chlorination: Chlorine gas is mixed into the water to  kill microorganisms.