Water Journal : Water Journal April 2011
refereed paper technical features 142 APRIL 2011 water water supply options explanation is that installing a tank results in a change in water use behaviour that is dependent on water use (connection options) and the relative abundance of tank water (tank volume). Thus large tank households in the 1-e and 3-elt groups may increase their total demand for water in response to their (normally) abundant supply of tank water, whereas 5-h households may be more circumspect with water use, accustomed as they are to being self-reliant for water. Increasing overall water consumption in response to rainwater tank installation is not without precedent; a recent study in South-East Queensland (Turner, Fyfe, et al., 2010) found that households with rainwater tanks used marginally more metered water than those that don't in the summer period, while in the winter period this was reversed. Conclusions Average water savings as a result of rainwater tank installation in the Rous Water supply area are calculated at 50kL/ house/annum; external use connections saved an average of 43kL/house/year; external, laundry and toilet connections saved 27kL/house/year; and all-of-house connections saved 107kL/house/year. The amount of water saved during any period is dependent on the type of connection, the underlying water demand, and to a lesser extent the tank volume. Choice of connections appears to be related to water use behaviour and external-only use connections seem to be preferentially chosen by households with a high proportion of external water consumption, so make low savings during low-demand (cool-wet) periods but increased savings during high demand (hot-dry) periods. External, laundry and toilet connections are low water users prior to tank installation, and so volume of water savings relative to pre-tank consumption is relatively small. All-of- house connections make very high water savings when demand is low; however, these savings rapidly fall as demand rises. Some level of increased overall water use appears to be occurring in houses with large tanks that have not connected for all-of-house use; these properties exhibit high metered water use during high demand (hot-dry) periods compared to properties with smaller tanks. The findings of this study will be used to further enhance water savings associated with Rous Water's Demand Management Program. Acknowledgements The author wishes to thank Robert Cawley, Future Water Strategy Manager, Rous Water, Elizabeth Seidl, Demand Management Coordinator, Rous Water and Antony McCardell, Lecturer, Southern Cross University. The Author Bevan McBeth has a BSc (Forestry) at Southern Cross University. He currently works as Project Officer on the Future Water Strategy at Rous Water, Lismore. (email: bevan.mcbeth@ rouswater.nsw.gov.au) References Australian Bureau of Statistics 2010: Environmental Issues: Water Use and Conservation, Cat no. 4602.0.55.003, ABS, Canberra. GeoLink 2005: Dunoon Dam: Population and Demand Projections, report prepared by GeoLink Environmental Management and Design for Rous Water, Lennox Head. Grafen A & Hails R, 2002: Modern Statistics for the Life Sciences, Oxford University Press, Oxford. Kirono D, Podger G, Page D & Jones R, 2006: Assessment of the Impacts of Climate Change on Water Supplies, report prepared by CSIRO Marine and Atmospheric Research (Climate Change Impacts and Risk) for Rous Water, Canberra. Lee L, Plant R & White S, 2008: THINK WATER, ACT WATER: Evaluation of the ACT Government's Water Demand Management Program, report prepared for Territory and Municipal Services by the Institute of Sustainable Futures, Sydney. Marsden Jacob Associates 2007: The Cost- effectiveness of Rainwater Tanks in Urban Australia, report prepared for the National Water Commission by Marsden Jacob Associates, Canberra. McCardell A, 2009: Rainwater Tank Model for Lismore, Lismore, 2009. NSW Department of Planning 2006: Far North Coast Regional Strategy: 2006-2031, NSW Department of Planning, Grafton. Retamal M, Turner A & White S, 2009: Energy Implications of Household Rainwater Systems, AWA Water Journal 36:8, 70-75. Rous County Council 1995: Strategy for long-term water supply -- policy adopted 16th August 1995, Rous County Council, Lismore. Rous Water 2005: Strategy for long-term water supply -- policy approved 21/12/2005, Rous Water, Lismore. Snelling C, Simard S, White S & Turner A, 2006: Gold Coast Water Evaluation of the Water Demand Management Program, report prepared by the Insititute of Sustainable Futures for Gold Coast Water and Qld EPA, Sydney. Teng M, 2009: Impacts of Rainwater Tanks on Small System Yield, AWA Water Journal 36:8, 76-79. Turner A, Fyfe J, Retamel M, White S & Coates A, 2010: SEQ's One To One Water Savings Program, AWA Water Journal 37:1, 82-91. Turner A, White S, Kazaglis A & Simard S, 2007: 'Have We Achieved the Savings? The Importance of Evaluations when Implementing Demand Management, Water Science and Technology: Water Supply 7:5-6, 203-210. Figure 13 (a-d): 3-dimensional representations of the statistical relationships between metered water use post-rainwater tank installation (mwu) by tank volume and water demand (srwc) for: a) all rainwater tanks; b) rainwater tanks connected for external use (1-e); c) rainwater tanks connected for external, laundry and toilet use (3-elt); and d) rainwater tanks connected for all-of-house use (5-h).
Water Journal March 2011
Water Journal May 2011