Chlorination of water supplies

Chlorination is the addition of chlorine to kill the bacteria Chlorination is very widely adopted for the treatment of water for public supply.

• Chlorine is available in gas, liquid or solid form (bleaching powder)
• It is cheap, reliable, easy to handle, easily measurable and capable of providing residual disinfecting effects for long periods thereby ensuring complete protection against future re-contamination of water in the distribution system

Advantages of chlorine

• Chlorine is manufactured easily by electrolytes of common salts (NaCl)
• It is powerful oxidant and can penetrate the cell wall of organism and its contents.
• Dosage can be controlled precisely
• It can be easily detected by simple orthotolidine test
• It does not form harmful constituents on reaction with organics of in-organic constituents in water
• It leaves required residue in water to neutralize re-contamination later.

Disadvantages of chlorine

• If used in excess it imparts bitter taste to water which might not be liked by sensitive tongued consumers

Precautions while using chlorine

• Chlorine gas or liquid is highly corrosive and lethal to inhale. Hence it is to be stored carefully in sealed container at a distance.
• If the water contains phenolic compounds, there is a reaction with chlorine can result in cancer causing substances.