Drinking water

Wannon Water has a comprehensive management framework for maintaining high quality drinking water. This includes an audited risk identification and management approach to water supply and catchment management and requires regular water testing and monitoring.

View Wannon Water's Zero Harm Policy.


Wannon Water conducts tests each year throughout the region from source waters through to treatment plants and up to the customer's tap. Compliance to the health standards in the Australian Drinking Water Quality Guidelines (2011) is the minimal water quality standard Wannon Water aims to supply to its customers.

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What we test for

Risks to health

Microbial tests
The most common and widespread health risk associated with drinking water is contamination by human or animal excreta. Pathogenic (disease-causing) microorganisms of most concern include bacteria, viruses and protozoa. The following tests are conducted:

  • Escherichia coli (E.coli) 
  • Coliforms
  • Plate counts.

Organic and inorganic chemicals
Wannon Water measures a range of chemicals to ensure the health risks in water supplies are minimised. The Australian Drinking Water Guidelines specify the limits for human health on a large number of parameters. Metals, radionuclides, hydrocarbons, herbicides, pesticides and a range of disinfection by-products from water treatment are all monitored, along with many other organic and inorganic chemicals.

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Taste, odour and appearance

Monitoring and testing is conducted to assess the taste, colour and appearance of water.

  • Physical parameters such as pH, turbidity, hardness, alkalinity and colour of water are measured
  • Chemical monitoring occurs to identify chemicals from the source water, which can also affect the aesthetic properties of water. 
  • Algae monitoring - algae can impact significantly on taste and odour.

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Operational monitoring

Wannon Water also undertakes a range of tests to assess the effectiveness of treatment. Monitoring disinfection by-products, physical parameters such as turbidity, and pH helps in assessing any operational issues with treatment and effectiveness of each treatment process. 

All the drinking water supplied by Wannon Water is treated and monitored to ensure that the quality meets the health standards as specified by the Australian Drinking Water Guidelines 2011. Depending on the system of supply, water will have undergone varying degrees of treatment, ranging from disinfection to full treatment via a water treatment plant.

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Water treatment

Wannon Water utilises a multiple barrier approach to ensure that drinking water is safe and aesthetically pleasing. The strength of this approach is that a failure of one barrier may be compensated by effective operation of the remaining barriers. This minimises the likelihood of contaminants passing through the treatment system and subsequently causing harm to consumers. The barriers utilised are:

  • Catchment management and source water protection
  • Detention in protected reservoirs or storages
  • Extraction management
  • Treatment
  • Disinfection
  • Maintenance of the distribution system.

Raw water from surface and ground water supplies may contain contaminates such as sediment, microorganisms and dissolved organic compounds. Such water may not be aesthetically pleasing, or safe to drink. To create a safe drinking supply Wannon Water treats the water through differing processes. The treated water is then reticulated through a number of storage tanks and pipes before being delivered to the customers.

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Treatment process

Depending on the system of supply, water will have undergone varying degrees of treatment, ranging from no treatment in regulated supplies, to full treatment via a water treatment plant. More information on the treatment process at your local water treatment plant, can be found on the information sheets page.


All drinking water supplied by Wannon Water is disinfected to ensure that micro organisms are eliminated.  There are three types of disinfection methods used by Wannon Water, namely Chlorination, Chloramination and Ultraviolet (UV).

Note:  A fourth type of disinfection occurs naturally via exposure of raw water to ultra-violet radiation (sunlight) in raw water storages.

Coagulation and Flocculation

Coagulation / flocculation is a process where a controlled dose of chemical coagulant / flocculant is added to the water. This results in fine particles joining together and forming larger particles (floc) that can be settled /floated or filtered from the water during the clarification steps.

Clarification and Sedimentation

Sedimentation of large particles occurs during water storage in the reservoirs and basins upstream of the treatment plants. Clarification is used to remove the remaining particles. This can be achieved by simply allowing the solids to settle to the bottom of a sediment tank or can be achieved by using a mechanical process to separate the floc from the clear water:

  • The slow upflow of water in an upflow clarifier allows the solid particles to sink, whilst clear water overflows at the top. 
  • Dissolved Air Flotation (DAF) relies on the injection of microscopic air bubbles into the water stream, causing floc particles to float to the surface. The particles are drawn off the surface and removed with a waste stream.

Clarification is aided by the use of chemical coagulants and or flocculants.

Cooling and Aeration Towers

When the source water is from an aquifer, the water may need to be cooled and/or treated to remove minerals such as iron. Cooling towers allow heat to be transferred from the hot bore water to the air.  Fans draw in fresh air to allow heat exchange to be maintained by avoiding an equilibrium being established, whilst a honeycomb structure is used to increase the contact between the air and water.  Iron removal is achieved when aeration causes soluble iron to oxidise and precipitate out. The particulate iron is then removed by either settling or filtration. 


Water is passed through a filter consisting of several types of graded filter media to remove remaining particles. Filtration is also effective in removing harmful pathogens such as Giardia and Cryptosporidium. At regular intervals each filter is backwashed to remove trapped particles from the filter media and to maintain filter integrity and water quality. 

pH adjustment

The adjustment of pH level is conducted to make coagulation more effective, make disinfection more effective and or to reduce the corrosiveness of the water. pH can be adjusted by adding acidic or alkaline solutions to the water. Wannon Water currently use carbon dioxide, caustic soda, soda ash and hydrated lime to adjust pH.


Sequestration involves the addition of sequestering agents followed by chlorination which keeps dissolved iron and manganese from oxidising and precipitating.

Iron Sorption

Iron sorption filters remove arsenic by adsorption.  Adsorption is a process where arsenic is attached to the surface of the iron sorption filter media that contain a large surface area.  Iron sorption is used as a polishing step to remove any residual amount of arsenic left in the water.


Oxidation is a process of converting a substance from a lower oxidation state to a higher oxidation state. Oxidation often results in soluble minerals becoming non-soluble. As a result of minerals becoming non-soluble, they settle out of the water. Minerals such as arsenic and manganese need to be oxidised to be removed by clarification and filtration processes. Oxidising can occur naturally by aeration or chemically by adding chlorine or other oxidising agents such as ozone and potassium permanganate.


Fluoride is added at Hamilton and Warrnambool in the form of Fluorosilicic acid. This is under the direction of the Department of Health (DoH) to help protect against tooth decay.  The DoH is the responsible authority in relation to information about fluoridated water supplies in Victoria.  Further information can be obtained on the DoH website.

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