Water treatment


Water Whys

Why do we treat our customers' drinking water and how do they know that it is safe to drink?

What chemicals are added to the water supply?

All drinking water supplies are treated to ensure the water is safe and aesthetically pleasing.

Typical chemicals added during the water treatment process are detailed below.

  • Small quantities of alum (Aluminium Sulphate) are added to the raw water. This chemical causes pollutants such as bacteria and sediments to form into larger clumps (known as flocculation) that can be extracted by a clarification/filtration process. In some cases, an additional chemical, known as a polymer, is also used.
  • An essential part of the treatment process involves the addition of a disinfecting agent to kill off any remaining bacteria that are not extracted during the filtration process. We use chlorine-based chemicals such as chlorine gas or sodium hypochlorite to disinfect the water. The amount of chlorine added is equivalent to less than half a cup in an average-sized backyard swimming pool. If too much chlorine is added, it can impact the taste and smell of the water. This process is therefore managed carefully.
  • Where water has to travel over long distances, ammonia is added to create chemicals (chloramines) which have superior disinfection characteristics. 
  • The addition of treatment chemicals alters the pH of the water. Lime or soda ash is added as a final step in the treatment process to restore the balance.

For more detail on what specific chemicals are added to each treatment facility please view our Annual Drinking Water Quality Report on the Water quality web page.

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What are non-potable water supplies?

Non-potable water is also referred to as non-drinking water, untreated water, raw water and, in some cases, regulated water.

Non-potable water is supplied to customers via transfer pipelines between our catchments and reservoirs/service basins prior to the water being treated e.g. the supply pipeline between the Grampians and reservoirs north of Hamilton. The colour of the water and the amount of fine sediment may vary significantly during the year.

Non-potable water is not treated and therefore does not necessarily meet Australian Drinking Water Health guidelines, particularly with respect to microbiological parameters. There is no protection against disease-causing organisms that may contaminate the water.

Customers receiving non-potable water are advised via their water account that the water is deemed not fit for drinking purposes. 

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What is potable water?

Water that is fit for drinking purposes is termed "potable" and must meet a number of strict health and aesthetic quality standards as specified in the Safe Drinking Water Act 2003.

Our region is serviced with a number of water treatment plants, and monitoring is undertaken to ensure this standard is maintained at all times.

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How do I know that my water is safe to drink?

All potable (drinking) water supplies are treated and routinely monitored to ensure that the supply remains aesthetically pleasing and safe to drink.

Drinking water must meet health and aesthetic criteria as specified by the Safe Drinking Water Act 2003. The Act includes reference to the Australian Drinking Water Guidelines which set limits for:

  • Pathogens - these are disease causing agents that include e-coli.
  • Physical and chemical criteria such as metals, turbidity, pH and other chemicals.

For more information, visit the Water Quality section or Contact Us.

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