Water Journal : Water Journal April 2011
refereed paper 136 APRIL 2011 water technical features water supply options Abstract Rous Water supplies potable water to approximately 100,000 persons in the Ballina, Byron, Lismore City and Richmond Valley Local Government Areas (LGAs) on the Far North Coast of NSW. This is an area of high and consistent rainfall, but with a growing population forecasts suggest water demand will exceed current supply between 2018 and 2030. A range of demand management strategies have been developed to delay the need to build new sources, including, from 2003, a residential rainwater tank rebate. This paper evaluates the metered water savings attributable to tank installation by households receiving this rebate and how these savings are affected by water demand, tank-house connections and tank volume. Results indicate average metered water savings of 50kL/household/year with tank installation, ranging from 27kL/household/ year for tanks connected for toilet, laundry and external use, to 43kL/household/year for external only connections, and 107kL/ household/year for houses connected for all-of-house use. Connection choices appear to relate to water use behaviour, with differences in pre-tank metered water consumption between groups choosing different connection options. Metered water consumption in properties receiving the rainwater tank rebate, both pre- and post-tank installation, is closely related to residential water demand in the greater community, but with reduced metered water use after tank installation. People who install large tanks yet do not connect them for all-of-house use seem to develop high water-use habits, with high rates of demand for reticulated water when tanks are empty. Introduction Widespread water restrictions during eastern Australia's prolonged drought of the 2000's highlighted the importance of conserving water held in centralised water storages. In response to this, rainwater tanks have been embraced by both governments and individuals as an important component of a secure water supply system. Recent estimates suggest that water tanks currently provide water to approximately 26% of Australian households, up from 19% in 2007 and 17% in 2004 (ABS 2010). In regional NSW the number of dwellings sourcing water from rainwater tanks is estimated at 28% (ABS: 2010). Rebates for the purchase and installation of household based rainwater tanks in the Rous Water supply area are currently provided by Federal, State and Local Governments. Rous Water supplies reticulated water to approximately 100,000 people in the Local Government Areas (LGAs) of Ballina, Byron, Lismore City and Richmond Valley on the Far North Coast of NSW (GeoLink: 2005). Although this region receives relatively high and consistent rainfall, the region's population is predicted to rise in the medium term (GeoLink: 2005; NSW DoP: 2006) and this is likely to place pressure on existing water supplies. Additional pressures include a "most likely" reduction in secure yield of 7.4% between 2006 and 2030 due to climate change (Kirono, 2006). Projections of future water supply and demand in the region have a large level of uncertainty, but generally suggest that demand for reticulated water will exceed current supply between 2018 and 2030 (GeoLink: 2005; Kirono, 2006). In response to forecasts of future supply shortfalls, Rous Water formally adopted a policy in 1995 (Rous County Council 1995) which included a demand management program and two new water sources. The first new source is the Wilson River Source, which was constructed in 2008 and extracts water from the Wilson River tidal pool near Lismore. The second is the proposed Dunoon Dam on Rocky Creek, which will be constructed at a future time depending on the adequacy of water supplies. This policy was last reaffirmed by Rous County Council in December 2005 (Rous Water 2005). B McBeth A detailed statistical analysis on usage between January 2002 and December 2009 SAVINGS FROM RESIDENTIAL RAINWATER TANKS ON THE NSW FAR NORTH COAST Figure 1: Rous Water Connections, Supply and Supply per Connection, 1988-2009. Data labels on the Supply line show total bulk water supply in ML/annum.
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