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Recycled water (Werribee)

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Werribee recycled water update - August

Melbourne Water supplies Class A recycled water to Southern Rural Water, which we distribute to our customers in the Werribee Irrigation District.

In recent years, several blue-green algae events, including an extended outage during the 2025-26 season, have affected the reliability of recycled water supplies. We understand these interruptions have impacted our customers and acknowledge the challenges created for farm planning and business operations.

Melbourne Water has provided Southern Rural Water with a partial refund in recognition of the extended recycled water outage for the time the plant was not operating during the 2025-26 irrigation season. We’re passing this refund on to customers.

We’re also implementing a temporary one-year variation to recycled water customer agreements for the 2026-27 season. 

Customers will soon receive an updated agreement for review and signature. If you want to access recycled water supply during the 2026-27 season you will need to sign and return this variation agreement 11 September 2026.

Under the new temporary arrangement, which only applies to the 2026-27 season:

• The current 50% take-or-pay charge would not apply.

• Customers would pay only for the recycled water they use.

• Customer costs will align to the delivery of recycled water during this period.

We’re working with Melbourne Water to improve the reliability and resilience of recycled water supplies in the Werribee Irrigation District. Melbourne Water is implementing a range of initiatives to seek to provide better remediation to the blue-green algae in coming years. This will include at least two technology trials that will be in place before peak summer 2026-27. 

We will continue to keep customers informed as work progresses.

If you have questions about the contract variation or billing arrangements please call our customer service team on 1300 139 510 or email srw@srw.com.au.

Background information on Blue-Green Algae impacting Recycled Water in the Werribee Irrigation District 

  • New safe trigger levels

    Melbourne Water has reviewed the trigger for resuming recycled water supply and updated it from 50,000 to 150,000 cells/mL for three days in a row, based on a safety assessment specific to agricultural irrigation. 

    The previous 50,000 cells/mL trigger was based on swimming guidelines. Additional precautions now apply, including extra toxin monitoring and restricting use to agricultural irrigation only while levels remain above 50,000 cells/mL.

  • What is 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 Melbourne Water’s Western Treatment Plant for Class A recycled water contains nutrient rich water which – when combined with warmer weather – create conditions for a variety of algae species to grow, including blue-green algae.

    The Blue Green Algae Emergency Response Plan, published by the Department of Energy, Environment and Climate Action (DEECA), includes guidance on the limits beyond which blue-green algae is considered a public health risk.

    For general use of recycled water, 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. For agricultural uses, Melbourne Water has reviewed the trigger for resuming recycled water supply and updated it from 50,000 to 150,000 cells/mL for three days in a row, based on a safety assessment specific to agricultural irrigation. 

    Southern Rural Water notifies our customers when the cell count reaches 10 percent of the limit as a safety reminder.

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

What is Melbourne Water doing to seek to tackle the BGA challenges?

  • What is the current peroxide treatment trial?

    A large-scale peroxide dosing trial started on 5 January 2026.

    This is the third year of peroxide trials that Melbourne Water has progressively scaled up from laboratory testing and small-scale pilot plant studies, through to a series of 24-hour tests at full-scale operation. Tests are advancing to continuous full-scale dosing over the whole bloom season. 

    So far, trials demonstrate scalability and efficacy, and it's likely to be the most feasible solution for blue-green algae control at waste stabilisation ponds.

  • When is the ultrasonic trial planned?

    A trial using a commercially available ultrasound unit for controlling blue-green algae is planned to be implemented in mid-2026.  

  • What other trials have been investigated?

    Copper based algaecides are commonly used to control blue green algae at small scales, particularly in water bodies that don't discharge to marine environments. Melbourne Water conducted a small-scale trial using coper-based algaecide in 2022 to determine its effectiveness and the rate at which copper was removed from the system.

    Copper is toxic to shellfish and other marine species at relatively low concentrations. Unfortunately, the trial showed that copper remained persistent in the process and was ineffective at controlling the algal bloom, making it not a viable option.

    No further trials using copper-based algaecides to control blue-green algae are planned.

    Investigations found that a small-scale trial using ozone would not be safe for staff to implement without costly and complex control measures.  

What's being done by the water authorities to secure a longer-term solution?

New Systems

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.  

In addition, Melbourne Water committed to investing in improvements to recycled water infrastructure as part of its Price Submission 2026-31. The investments included the renewal and improvement of chlorine treatment infrastructure to be delivered by 2028/29, additional treatments for blue green algae to provide reliability in 2027 and carbon dioxide dosing upgrade to improve pH and reliability.

Re-thinking our contracts

1 July 2026 signals the start of a new contract period for recycled water supply to WID customers. We’re re-thinking how to approach the next contracts and will be working with customers in the coming months to seek to understand how the next year could work differently from a contractual perspective, acknowledging this is the 4th year of BGA impacting recycled water supplies. 

Winter roster and maintenance period

Our critical maintenance work is now underway as part of our May–September maintenance period. These works are scheduled during non supply times to minimise disruption and help customers plan their winter irrigation.

Providing there is enough demand, water will be available to WID irrigators from Monday afternoon to Friday afternoon on the rostered dates, depending on demand. If demand is low, orders may be moved to another day, and our planners will contact you if this occurs.
 

Contact us         

If you wish to lodge a complaint, Southern Rural Water is committed to responding or passing on complaints or feedback as appropriate.

Please call 1300 139 510 or email srw@srw.com.au

Our Customer Charter can be found here.

  • 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.

  • 2024/2025 recycled water outage

    Recycled water customers were provided with a rebate in recognition of the extended recycled water outage for the time the plant was not in operation during the 2024/25 irrigation season. This included a prolonged outage from 1 February to 7 May 2025, resulting from an outbreak of Blue Green Algae at Melbourne Water’s Western Treatment Plant.  

    Melbourne Water provided Southern Rural Water with a rebate in recognition of the extended recycled water outage for the time the plant was not operating during the 2024/25 irrigation season.  

    Southern Rural Water passed on this rebate in full to its customers.  

    Melbourne Water calculated the rebate based on the cost savings achieved when the plant was not in operation. This was equally applied to each customer proportional to their contract volume.  

  • 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 2004 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.

 

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.

2025