Integrated Urban Water Cycle

Abstract

This paper looks at water sensitive urban design in its broadest context incorporating water supply, wastewater, and stormwater services. It is our thesis that cost reduction and reconsideration of the economics of water supply, wastewater and stormwater services, combined with re-examination of emerging technologies and customer attitudes, will expand the range of options available to be adopted in particular circumstances. It is our further contention, that no one solution is appropriate for all circumstances, and that increases in the range of options available will lead to better tailoring of water systems to site specific conditions. The paper outlines some of the outcomes of the CSIRO Urban Water Program that point to the opportunities to take an integrated approach to the urban water cycle. Establishment From the outset, it is essential that we establish what aspects of urban water systems we are referring to in discussion water sensitive urban design. Perhaps because we consider reticulated water and sewerage systems as being artificial, and rainwater as natural, there has been a tendency firstly to consider effective management of stormwater as being the principal focus of water sensitive urban design. Significant effort has been directed to conceptualising means by which natural surface water flow patterns can be mimicked; similar levels of attention need to be paid to improving the performance of underground water and sewer reticulation systems. Furthermore, it is the integration of water supply, wastewater and stormwater that should be a fundamental principle underpinning water sensitive urban design. The following quote encapsulates this concept: “water sensitive urban design is the application of a wide range of within catchment measures to manage the impacts of urban developments on the total water cycle” (WBM Oceanics Australia, 1999). Consider some examples. Retardation of stormwater for later discharge also provides a store of water that could be used for, say, toilet flushing or washdown water, where potable quality water is not required. Reduction of potable demand, in turn, reduces dependence on remote water sources, possibly allowing more water to be made available for environmental flows or obviating the need for new dams to be constructed. Similarly, transfer of sewage under pressure or by vacuum would reduce ingress into sewer systems, allowing sewage treatment plant performance to be optimised, reducing