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Werribee Recycled Water Update

Class A recycled water supply to the Werribee Irrigation District is set to resume on 8 May 2025 after a prolonged outage (1 February to 7 May 2025) resulting from an outbreak of Blue Green Algae at Melbourne Water’s Western Treatment Plant. 

Southern Rural Water has been working closely with Melbourne Water to support the earliest possible resumption of supply in addition to a suite of interventions that aim to enhance supply reliability for future years. 

More information: 

Why was there a prolonged outage? 

Blue Green Algal blooms occur naturally in waterways, wetlands and water storages. An extended period of warm and dry conditions since the start of 2025 provided the right environment to trigger blooms in the treatment plant lagoons at Melbourne Water’s Western Treatment Plant. 

Blue Green Algae blooms produce toxins that are harmful to human health. Strict regulations and controls mean that recycled water has not been supplied while high Blue Green Algae readings have been recorded. Please read Agriculture Victoria’s blue green algae factsheet for more information.  

What is being done to fix the problem? 

Southern Rural Water and Melbourne Water are working closely on research trials to manage future Blue Green Algal blooms. 

Three methods currently being explored include: 

  • Hydrogen peroxide dosing 

  • Ozone dosing 

  • Ultrasonic treatment 

Early trials of each of these treatment methods have been completed with a pilot plant for ultrasonic treatment pilot project now planned for construction in the coming months.  Ultrasonic treatment involves firing ultrasound waves through an Algal bloom disrupting the cell structure and destroying the Algae.  

The objective of this project is to control large outbreaks of Blue Green Algae in Melbourne Water’s treatment lagoons, which, if successful, will improve the reliability of recycled water supply in future years. 

How will customers be compensated for this outage?   

Southern Rural Water and Melbourne Water are working in good faith with Werribee Growers in recognition of the prolonged period of supply outage.   

In similar cases of prolonged supply outage in 2022 and 2024, Melbourne Water has provided a rebate to Southern Rural Water on its recycled water contract payments.  This rebate has been passed on by Southern Rural Water to Werribee Recycled Water customers in full.   

Melbourne Water and Southern Rural Water are in discussions on a potential rebate on 2025 recycled water contract payments given the prolonged period of outage (1 February to 7 May 2025).  Any rebate will be calculated at the end of the financial year, and the full amount of any rebate will be passed through to Werribee Recycled water customers by Southern Rural Water.  

What is being done to secure a longer-term solution? 

Southern Rural Water and Melbourne Water are both committed to securing a high-quality, reliable recycled water product for Werribee growers through the Werribee System Reconfiguration project. 

Growers and our project partners Department of Energy, Environment and Climate Action, Melbourne Water and Greater Western Water have pledged their support for the preliminary business case. 

We submitted a funding application for further developing the business case to the National Water Grid Authority and we’re awaiting a final decision. 

  • Introduction of the Recycled Water scheme

    The Werribee Irrigation District is an important vegetable growing area on the western fringe of metropolitan Melbourne. Using water from the Werribee River, the aquifer below and the recycled water scheme, over 400 growers produce lettuces, broccoli, cabbages and many other vegetables for local consumption and export.

    During 1994 the then Victorian Minister for Water, John Thwaites, announced the Werribee Irrigation District Recycled Water Scheme would be established. The scheme was designed to assist in overcoming water shortages due to drought and to secure water for greater production in the future.

    During 2004 grower representatives, project partners (Department of Energy, Environment and Climate Action, Melbourne Water and Southern Rural Water), and regulators (EPA Victoria and Department of Health) took up the challenge of bringing the scheme to fruition.

    More than $20 million was invested in additional water treatment at Melbourne Water’s Western Treatment Plant, a connecting pipeline into the Werribee Irrigation District, environmental investigations and approvals, and the operating arrangements for the scheme. Growers received the first deliveries of Class A recycled water under the scheme in January 2005.

  • Class A recycled Water

    Class A recycled water is supplied by Melbourne Water and delivered to participating growers by Southern Rural Water through its existing irrigation channels and pipelines.

    Class A recycled water is water that has been collected from the sewage catchment and treated to make it safe for a wide variety of non-drinking uses.

    The process used to ensure the Class A recycled water is safe for its intended use is strictly regulated by the Environment Protection Authority (EPA) Victoria.

    The treatment process consists of multiple stages of treatment that remove different types of compounds. At the Western Treatment Plant (WTP) we use three stages of treatment, primary, secondary and tertiary:

    • Primary treatment involves physical removal of large pollutants such as plastics, rags and other material that will sink or float.
    • Secondary treatment involves biological removal of compounds like ammonia, nitrogen, carbon and other dissolved compounds.
    • Tertiary treatment involves disinfection to kill residual pathogens left in the water, such as bacteria, protozoa and viruses.

    It is important to remember that although Class A recycled water has been treated for reuse, it should only be used for its intended purpose. For more information on recycled water, visit Melbourne Water.

  • Uses of Class A recycled water

    Class A recycled water can be used for a wide range of non-drinking purposes including for the irrigation of food crops intended for raw or unprocessed consumption. 

    It should not be used for drinking, cooking, showering, filling domestic swimming pools or drinking water for pigs. 

    Class A recycled water is supplied by Melbourne Water who follow strict state and national guidelines for producing recycled water.

  • Class A recycled water and blue-green algae

    Blue-green algae is a naturally occurring group of micro-organisms present in both fresh water and salt water. Under certain environmental conditions, these cells can grow rapidly or ‘bloom’. The lagoon treatment process at the Western Treatment Plant contains nutrient rich water, and when combined with warmer weather, create conditions for a variety of algae species to grow, one of which is blue-green algae.

    The Victorian blue-green algae circular, published by the Department of Energy, Environment and Climate Action (DEECA), includes guidance on the limits (cells/mL) beyond which blue-green algae is considered a public health risk.

    Melbourne Water follows the recommendations set by DEECA and will cease supply of Class A recycled water if the blue-green algae cell count exceeds the limit published in this guide for swimming. A notification is sent to Southern Rural Water customers when the cell count reaches 10% of the limit to remind customers to limit their exposure to the water.

    More information about blue-green algae can be found on our blue-green algae warning page.

 

Using Class A recycled water for irrigation

For information on Shandy Mix salinity levels visit Waterline. 

Western treatment plant recycled water quality

Click the links below to access the “western treatment plant recycled water quality – Post disinfection” report for the corresponding month.