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Melbourne's water supply

Melbourne's water supply comes from a series of natural, protected catchments located to the north and east of the city.

In these catchments public access, recreational use and any other activities which could adversely affect water quality are restricted.

This means that only minimal disinfection of the water is required to ensure health and safety.

Other than distilled water, all water contains some chemicals. These chemicals dissolve in water as it passes through the atmosphere and the soil. 

To ensure the provision of clean, safe water a great deal of scientific research has led to the development of guidelines for the use of chemicals in water treatment. The guidelines require small amounts of chemicals to be added to the water supply.

The chemicals added to your water supply include: 

  • Chlorine (gas or liquid ) - Chlorine is used widely throughout the world to disinfect and remove the risk of water-borne diseases, such as gastroenteritis (a stomach bug). 
  • Chlorination is the main method of disinfection for Melbourne's water. However, in some outlying areas of Melbourne other methods of disinfection, namely chloramination and ultra violet radiation are used. Find out more about chlorination.
  • Fluoride - Small amounts of fluoride are added to the water at the direction of the health authorities, for dental health reasons. Adding fluoride increases its natural level in the water and helps to develop resistance to tooth decay in children and adults. The amount added is equal to about one grain of sugar in a cup of water. Find out more about fluoridation.
  • Lime / Soda Ash - Lime and soda ash are used to lower the pH levels of water to neutral (ph 7) (neither acid nor base) after fluoride and chlorine have been added. They are also added to the water to prevent corrosion and reduce the formation of scale (a crust that can form on pipes and other water supply fittings).
  • Poly electrolytes - Poly electrolytes trap suspended particles, microorganisms and colour which naturally occur in the major storage reservoirs. Poly electrolytes used during the treatment process are removed from the water before it reaches your tap.

For a small amount of water that we supply (about 10 per cent), aluminium sulfate is added to the water to remove sediments and make it clean and clear.

The addition of these chemicals is continuously monitored and controlled to ensure that the correct amounts only are added to our water. 

Sometimes there are problems with the quality of water that comes out of our taps. Generally, the most common problems occur closer to the destination and can be easily fixed.