Water Purification

Flocculation
The water is passed through tanks where a number of chemicals are added, including coagulants such as aluminium or iron sulphate. These form a dense layer called floc on which impurities such as colour, suspended din, bacteria and metals stick.
Clarification
The floc is separated from the clarified water by one of two processes, Sedimentation, the floc settles beneath the surface of the water, concentrating in a cone shaped bucket to a draw off pipe. The clarified water at the top passes through to the next stage.
Dissolved Air Flotation
Air in the form of small bubbles is injected from the bottom of the tank. This floats the floc to the surface of the water where it is scraped off by brushes. The clarified water beneath the floc layer passes through to the filters.
Filtration
The clear water is passed through filters consisting of a bed of fine sand supported on layers of coarse sand and gravel. The fine sand removes traces of residual coagulant and suspended matter. The sand is washed frequently, by reversing the direction of flow.
Chlorination
Chlorine is added to protect against any remaining harmful germs.
Water stabilisation
It is often necessary to add lime to the water to ensure that the customers' pipe work are protected against corrosion.
Sampling
To ensure that the water is safe for drinking purposes many samples of water are taken from within the treatment process and the distribution system, including customers' houses.

Water Purification Hard Water Testing Softeners Filters