The Impact Of End-Use Dynamics On Urban Water System Design Criteria

Water authorities throughout Australia are facing considerable challenges to satisfy increasing demand in the face of historically low rainfall and inflows. This has lead to the emergence of the paradigm of integrated urban water management (IUWM). The IUWM design paradigm places a greater emphasis on household and cluster scale water management solutions such as raising public awareness, implementation of domestic water restrictions, provision of demand management incentives (installing water saving appliances) and support for source substitution approaches including rainwater tanks and greywater recycling. As the IUWM design paradigm becomes more popular the questions arises how this will impact on common design criteria such as average and peak demand/wastewater flows. This paper provides a preliminary investigation into this issue. Effective and efficient design using the IUWM paradigm relies on a greater understanding of the dynamics of household water use at spatial and temporal scales smaller than those traditionally adopted for such design work. For example to determine the impact of demand reduction strategies such as source substitution or installing water saving appliances requires knowledge of the dynamics of various household end-uses, such as shower, toilet, washing machine, tap and outdoor use. Flow trace analysis, pioneered in the USA by De Oreo et al. (1996) is a popular technique for measuring end-uses. Flow-trace analysis has been used in Australia in the Perth Domestic Water Use Study (DWS) (Loh and Coghlan, 2003) and the Yarra Valley Water (YVW) residential end-use monitoring study (REUMS) (Roberts, 2005; 2006). Both these studies provided very useful insight into the end-use characteristics averaged over a large group of houses. However neither study investigated the end-use dynamics and its impact on common urban water system design criteria. 

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