RegionalDevelopment Implications of Wastewater Reuse: Werribee Case Study

ReportNo WSAA 70

November 1993

SYNOPSIS

Theexisting water resources which supply Melbourne’s potable water needs arefinite and the current 2.2% annual increase in demand for water is notsustainable far into the next decade. In the past, Melbourne, like othercities, has increased its supply of water by damming or diverting more rivers.In the future, it will be necessary to consider redistributing the nation’stotal water resources or resort to alternative water sources, like ground wateror the use of recycled water, in order to meet our future needs.

Seriousconsideration is now being given to the possible use of recycled water as asource of non-potable supply to new and existing communities. Many overseascountries have already introduced recycled water systems as part of theirstrategies for the future.

Amajor urban land developer had prepared a Local Structure Plan for an area ofland which totals 1320 ha at Werribee, demonstrating the potential to support apopulation of more than 50,000 people. Earlier investigations undertaken intothe potential development of land for urban use in this area, identified theopportunity of utilising existing Rural Water Corporation irrigation waterstorages as sources of potable water for new urban areas. The existingirrigation supply would be replaced with treated waste water from the WerribeeTreatment Complex, for irrigation of both public land and private gardens,toilet flushing and for use within ornamental water features.

Thisresearch project has set out to determine the level of treatment required to beapplied to the waste water to enable it to be used for recycling, the level ofdemand expected for waste water re-use, what opportunities exist now and in thefuture for waste water recycling, what are the costs of producing a suitablequality effluent and what benefits flow to the community from the use ofrecycled waste water.

Theproject has identified that there is considerable international and localexperience in the operation and management of water recycling systems supplyingtreated waste water to residential properties, to support the introduction ofsimilar schemes in Victoria.

Theconclusions of the project are that there is benefit in the substitution ofrecycled waste water for non-potable uses, that the irrigation of the marketgarden areas with highly treated recycled water, as a substitute for irrigationwater, may require that the price of the waste water be subsidised through thesale of the irrigation water supply for potable uses. The project has furtherconcluded that there are economic advantages in the use of local treatmentplants and waste water recycling systems, in preference to the continueddischarge of sewage to the large existing treatment complex.

Theproject further concluded that the level of dissolved salts in the treatedwaste water produced from the Werribee Treatment Complex is high and actionshould be taken to reduce the levels to enhance the use opportunities for thatwater.

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