Water treatment plants convert the raw untreated water to consumable water that is available at your home. The stages of water treatment:

  1. Sedimentation: Large particles are screened out and smaller particles are left to settle to the bottom of the sedimentation tanks.
  2. Flocculation: Aluminium sulphate (which is a flocculating agent) is added to cause the small, suspended particles to stick together to form larger heavier particles.
  3. Filtration: Water is filtered through beds of sand and gravel which removes the remaining suspended particles.
  4. Chlorination: Chlorine is added to kill bacterias and micro-organisms that may be present in the water.
  5. Fluoridation: Fluoride is added to strengthen teeth and to prevent tooth decay.
  6. pH adjustment: Water is adjusted to have a pH in the range of 6-8. If the water is too acidic (pH is low), it may corrode pipes, so calcium hydroxide is added to raise the pH level. If the pH is too high, it is lowered by adding sulphuric acid.