Regional Development Implications of Wastewater Reuse: Werribee Case Study

This report was produced for the Urban Water Research Association of Australia, a now discontinued research program.

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Report no. UWRAA 70

November 1993

Synopsis

The existing water resources which supply Melbourne’s potable water needs are finite and the current 2.2% annual increase in demand for water is not sustainable far into the next decade. In the past, Melbourne, like other cities, has increased its supply of water by damming or diverting more rivers. In the future, it will be necessary to consider redistributing the nation’s total water resources or resort to alternative water sources, like ground water or the use of recycled water, in order to meet our future needs.

Serious consideration is now being given to the possible use of recycled water as a source of non-potable supply to new and existing communities. Many overseas countries have already introduced recycled water systems as part of their strategies for the future.

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

This research project has set out to determine the level of treatment required to be applied to the waste water to enable it to be used for recycling, the level of demand expected for waste water re-use, what opportunities exist now and in the future for waste water recycling, what are the costs of producing a suitable quality effluent and what benefits flow to the community from the use of recycled waste water.

The project has identified that there is considerable international and local experience in the operation and management of water recycling systems supplying treated waste water to residential properties, to support the introduction of similar schemes in Victoria.

The conclusions of the project are that there is benefit in the substitution of recycled waste water for non-potable uses, that the irrigation of the market garden areas with highly treated recycled water, as a substitute for irrigation water, may require that the price of the waste water be subsidised through the sale of the irrigation water supply for potable uses. The project has further concluded that there are economic advantages in the use of local treatment plants and waste water recycling systems, in preference to the continued discharge of sewage to the large existing treatment complex.

The project further concluded that the level of dissolved salts in the treated waste water produced from the Werribee Treatment Complex is high and action should be taken to reduce the levels to enhance the use opportunities for that water.

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