Living on the edge comparing urban water systems

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What’s the best way to assess and compare alternative water systems?

Jill Fagan reckons most models in use have serious drawbacks and she’s been developing a new way to compare urban water systems by taking a whole-of system view. Jill is an eWater CRC PhD candidate at the Department of Civil and Environmental Engineering, the University of Melbourne.

Her method is being demonstrated at Aurora, a new suburb of 8,500 households on the northern edge of Melbourne. The suburb is expected to achieve in excess of 55% water savings by using a range of innovations. These include a suburban-scale wastewater treatment plant and water recycling to every dwelling, energy efficient homes, gas-boosted solar hot water systems, provision for rainwater harvesting, biofiltration swales and wetlands.

The modelling indicated that installation of water-efficient household appliances leads to a 27% reduction in total water consumption. If, on top of this, recycled water is used in washing machines, and rainwater tanks supply hot water systems, there’s a dramatic reduction in the peak demand for potable water (on an average day). This implies that water supply pipes could be smaller, which leads to large capital cost savings.

The model also demonstrated that installation of water-efficient appliances not only saves water, but also reduces greenhouse gas emissions and energy consumption from operation of household water-using appliances. “This result is even more significant when you see it in the wider context. For Aurora, my modelling has shown that water-related energy consumption by households is on average ten times that consumed in the rest of the urban water cycle combined,” explains Jill.