Eastern Irrigation Scheme

About the Eastern Irrigation Scheme

TRILITY’s Eastern Irrigation Scheme was one of the first Class A water recycling schemes in Australia, the Scheme operates under the brand TopAq, a wholly owned subsidiary of TRILITY Group. TopAq will own and operate the scheme for 25 years.

Today this scheme remains one of Australia’s largest water recycling scheme providing Class A recycled water for residential use and food production.

In May 2014, Melbourne Water commenced the supply of Class A recycled Water from the Eastern Treatment Plant following a substantial upgrade and augmentation of this plant with construction of the Advanced Tertiary Treatment Plant. Thus the need for Water Infrastructure Group to operate the Class A treatment plant at the EIS Site has become redundant.

Class A recycled water is distributed through a 60 km pipeline network to 80 customers in a 170 square km area around Cranbourne.

TRILITY’s Eastern Irrigation Scheme has additional recycled water available for supply to customers. Any new or additional supplies can only be undertaken where there is existing capacity in the pipe network, this can be checked by reference to the Recycled Water Manager.


Recycled water customers include horticultural, recreational and industrial users keen to replace expensive potable water.
The Class A recycled water is of a quality that enables primary producers to sell their produce reliably to major retailers and is approved by the Environmental Protection Authority (EPA) as safe for watering all crops.
Class A recycled water from the Eastern Irrigation Scheme is also being supplied to South East Water Limited for dual pipe use in residential developments as a substitute for potable water for toilet flushing and garden watering.
Customers have long-term renewable contracts for supply, which enables these businesses to plan with the certainty of a guaranteed, high quality water supply.

Undertaking by Customer

All customers are required to undertake application of the recycled water in accordance with their property Environment Improvement Plan (EIP) and to complete and submit on an annual basis the Compliance Certificate. This information is outlined  in the customers EIP.

Compliance certificate

Water Quality

The Class A water quality delivered by the Eastern Irrigation Scheme is constantly tested by regular sampling and analysis. The results reported quarterly and can be viewed by clicking the links below:

Results January – March 2024

Results April – June 2024


Previous results

| 2023 | 2022 | 2021 2020 | 2019 2018 2017 | 2016 | 2015 | 2014 | 2013 | 2012 | 2011 | 2010 | 2009 | 2008 | 2007 | 2006

Eastern Irrigation Scheme facts

    • Total Capital Value – $25m
    • Total Annual Volume – up to 6,000 ML
    • Commencement of Supply of Class A Recycled Water – May, 2005
    • TopAq will own and operate the Eastern Irrigation Scheme for 25 years
    • 60 km of pipeline supplying 80 customers

Backflow prevention

Backflow of any water from the customer’s property into the TopAq pipeline system must be presented to avoid cross contamination. TRILITY staff regularly inspects the customer’s systems and if any contamination is detected supply will be stopped. It is therefore very important that all customers comply and:

    • complete the section in the Compliance Certificate which is submitted each year; and
    • strictly follow the Customer Rules

Should any customer require assistance or is unsure, then please contact an operator. Contact details are provided.

Outlet/meter connection

TopAq staff will regularly inspect the meters and take the readings. Should any customers notice these to be malfunctioning, then they are requested to call an operator immediately to register the problem. The Scheme does not guarantee a delivery pressure, however provides for a flow rate set at 0.75% of the Annual Contract Quantity. In some circumstances orifice plates have been fitted to assist in the management of the reticulation system.


From time to time leaks will be observed from pipelines or structures such as air valves/tappings etc. Most of these occur due to ground movement and a corresponding movement of joint / fitting or a failed fitting. Customers are requested to contact the duty operator on phone number 9770 8145 if any leak or suspected leaks/bursts are observed. If this number is engaged or unavailable, then contact South East Water on phone number 9552 3113. TopAq has an arrangement with South East Water for the management and repair of recycled pipeline bursts.

Can I connect to the Eastern Irrigation Scheme or get delivery of recycled water?

TopAq has experienced unprecedented demand for the supply of recycled water due to the dry weather conditions. The demand has occurred 4 years earlier than estimated and has used up all the surplus capacity in the Scheme. Therefore there is no further recycled water available for new or existing customers at this time. TopAq is currently investigating options for expansion of the Scheme, however additional volumes will not be available for this summer period.

Supply to new customers is subject to location and generally within close proximity of the Scheme pipelines. Should new customers fit the criteria above, then TopAq can assess on an individual basis the associated costs and whether a supply can be made available. To do this it is necessary to submit details of the location of the property to be supplied and the required annual quantity (must be greater than 10 megalitres per annum). TopAq will assess this written request and respond.


TRILITY operates the Scheme on behalf of TopAq. Full-time operators are based at the Eastern Irrigation Treatment Plant.

Eastern Irrigation Scheme Treatment Plant

T: 9770 8145 (8am-4pm Mon-Fri)
An after hours answering service will provide contact details for the after hours duty officer.

TRILITY Contacts

Eastern Irrigation Scheme Team Leader
David Aitken
M: 0438 029 782
E: daitken@trility.com.au

Eastern Irrigation Scheme Process Controller
Mark Rutherford
M: 0409 131 994

Eastern Irrigation Scheme Process Controller
Troy Jones
M: 0447 346 898

Regional Operations Manager
Kai Wallasvaara
M: 0477 708 187

Today our combined services consist of:


  • Asset management
  • Innovation
  • Wastewater treatment
  • Water quality
  • Water treatment


  • Audits
  • Modular solutions
  • Network services
  • Project delivery
  • Servicing


  • Audits
  • Compliance
  • Data analytics & management
  • Environmental management
  • Water consultancy
  • Water quality plans


  • Nationally recognised training
  • NTA certificate courses
  • Non-NTA training courses


  • Chemical dosing
  • Components and instrumentation
  • Electrochlorination
  • Filtration
  • Gas chlorination
  • UV disinfection