Water Journal : Water Journal November 2012-1
refereed paper demand management water NOVEMBER 2012 89 All three programs encourage tank capacity greater than 2,000 litres to ensure sufficient rainwater can be collected, require a licensed plumber to install the rainwater tank, and require it to be fully operational to be eligible for the rebate. GCC maintained a rainwater tank rebate approval record. This record was used to estimate the rainwater tank uptake rate. Household survey To better understand the factors affecting the installation of rainwater tanks and water-efficient devices in the community, a limited household survey was conducted as part of the project. The survey was also an opportunity to study the water usage behaviours of households and methods being used by households to reduce their water consumption and/or wastage. The focus of the survey was the community of Gosford Local Government Area (GLGA). To ensure a mix of participants over different household sizes and incomes, each suburb within the GLGA was categorised by the suburb’s average household income (Modessa, 2010). Using a list of all GLGA suburbs provided by GCC and the Australian Bureau of Statistics 2006 Census database (ABS, 2006) for ‘Gross Household Income (Weekly) by Suburbs’, each GLGA suburb was classified by the average household income. There were about 62,817 households within the GLGA, as of 2006. A sample size of 140 households was selected for the household survey as this provided a maximum sampling error of plus or minus 8.28% at 95% confidence interval. However, satisfactory responses were received and used for analysis from only 100 households. Table 3 presents the distribution of households with respect to the income groups. Although the target was to survey about 20 households under each income group, it was possible to survey only two households under the income group of $1,700– $1,999 (Modessa, 2010). The household surveys were undertaken through telephone interviews (this mode of household surveying was selected due to both budget and time constraints on the project), which was carried out from Gosford City Council’s office. Households were randomly chosen and participants were required to be adult residents of the household to ensure the most accurate data. Rainwater Tank Uptake Rainwater tank uptake rates were estimated using both Council’s rebate approval records and the data collected from the household survey. Council’s rebate approval data Studies have shown reduction in town water supply can average between 42 and 47L/capita/d if the rainwater tanks supply both internal and external non-potable water demand of a typical home (Beal et al., 2011). However, the effectiveness of a rainwater tank is largely dependent on rainfall, roof catchment area, tank size and household consumption. Since the Gosford Council Rainwater Tank rebate program began in 2003 and ran up until the end of November 2009, 5,799 households (approximately 9.5% of GLGA households, which was 63,091 in 2009) received a rebate from the program. Table 4 highlights a strong preference for rainwater tank sizes ranging between 2,000L and 7,000L during the Gosford Council Rainwater Tank Rebate scheme. Figure 4 presents the number of rainwater tank rebates approved per year in the Gosford Local Government Area, as well as the number of internal connections made since the Gosford Council rebate began in 2003. As shown in Figure 4, the rainwater tank approvals peaked in 2006 and 2007, which coincided with the introduction of more stringent water use restrictions of Levels 3 and 4 (Figure 1 and Table 1) as well as the sharp increases in the price of water from 2005 (Figure 3). The introduction of more stringent restrictions on water use and higher water prices appear to have contributed towards the higher uptake rates of rainwater tanks than the rebate scheme alone. As shown in Figure 4, by 2009, with the three rebates on offer to the residents, there was an opportunity for households to save up to $2,500 on their rainwater tank purchase. Despite this financial incentive, approvals for rainwater tank installation were substantially less than in previous years. This can be attributed to the easing of severe water restriction in the middle of 2009 (Table 1). However, in 2009 the fraction of internally plumbed tanks exceeded the number of external only connections for the first time, presumably to obtain the Australian Government subsidy, which was conditional on internal connections (Table 2). There was a strong uptake of rainwater tanks in 2006 and 2007 with 1,736 and 2,333 approvals respectively, which would have been influenced by the Level 4 water restrictions, which saw a total ban on the use of town water for external uses commencing in October 2006 and remaining in place until June 2009. Table 3. Number of households selected for survey. Gross Weekly Family Income Group Household Size Total 123456 $650-$799 211421-20 $800-$999 28313320 $1,000-$1,199-7381120 $1,200-$1,39915435220 $1,400-$1,69928161-18 $1,700-$1,999 - - - - 2- 2 Total 7391520136100 Table 4. Installations by rainwater tank capacity. Capacity Count 7,000L or greater 735 4,000–7,000L 2,660 2,000–3,999L 2,404 5000 6000 2500 3000 Line – Cumulative Column - Yearly 4000 5000 2000 2500 alsear Restriction Level 3 / 4 introduction 3000 1500 TotalApprovaAppovalsperYe GCCR 1000 2000 500 1000 AGR NSWGR 0 0 2003 2004 2005 2006 2007 2008 2009 Rebate Year A dRitTkItllti Et lUOlC ti BthEt ldItlC ti Approved Rainwater Tank Installations External Use Only Connection Both Extrernal and Internal Connections GCCR – Gosford City Council Rebate; NSWGR – NSW Government Rebate; AGR – Australian Government Rebate Figure 4. Number of approvals for rainwater tanks in GLGA.
Water Journal December 2012
Water Journal September 2012-1