Water Journal : Water Journal March 2011
refereed paper smart water systems & metering water MARCH 2011 93 This represented a per capita average of 145.3L per person per day (L/p/d) (Figure 3). The water use averages fell well below the Permanent Water Conservation Measures (PWCM) target of 200L/p/d as recommended by the Queensland State Government. Furthermore, the average water consumption for the regions monitored were roughly equivalent to the water use achieved during previous enforced high- and medium-level water restrictions. This is an encouraging indication that there is some long-term behavioural shift by residential water consumers, even though SEQ dams are recording close to full capacity and there has been a prolonged relaxation on external water usage. End use breakdown on a per capita basis indicated that, on average, showers (42.7L/p/d: 29%), taps (27.5L/p/d: 19%) and clothes washers (31L/p/d: 21%) comprised the bulk of the water consumption (Figure 3). Almost 70% (approximately 100L/p/d) of total consumption was attributed to these three activities. The water consumption activity breakdown is shown in Figure 4. Water end use breakdowns varied substantially across (and within) the regions examined. This variation is a reflection of several factors including family size and composition, socio- demographic factors and climate. In all the homes measured, there was water use from the toilet, clothes washer, taps and showers. The remaining end uses analysed (leaks, dishwasher, irrigation and bath tub) were reported in some, but not all, of the homes. Figure 3: Average daily per capita water end use breakdown for combined SEQ regions. Interestingly, water consumption for irrigation and general outdoor purposes was found to be low, at an average of only 7L/p/d, which is less than 5% of total consumption (Figure 3). The distribution for irrigation (Figure 4) indicates that half the homes monitored did not register any irrigation use during the period of analysis. The lack of irrigation could be attributed to the winter season when outdoor watering is usually lower than the hotter summer climate. Rainfall prior to the measurement period may also have reduced the need for watering. Additionally, there may be a tendency for lower external watering to occur due to the change in behaviour as a result of the water restrictions adhered to during the relatively recent drought period. However, of the homes that did irrigate (or use water for external purposes), 20% contributed to over 80% of total irrigation water use at an average of 30L/p/d. This pareto effect has been observed in other residential water use studies (Willis et al. 2009a; Turner et al. 2009) and is a good example of why water restriction policy focuses on outdoor use to reduce residential demand (Barrett & Wallace 2009; Inman & Jeffrey 2006). Irrigation has historically been a key contributor to average and peak day demand. However, this study reconfirms other recent findings (Willis et al., 2009a) that irrigation may be sustainably reduced into the future and may not return to 30- 50% of total residential potable demand (eg, Loh & Coghlan, 2003; Roberts, 2005); summer end use sampling will reinforce this hypothesis. Regional water consumption In terms of water consumption between regions, there were some clear variations between total water use and some end uses on both a per capita and household basis (Figure 5). Properties located in the Sunshine Coast consumed the most water per capita (171L/p/d) and per home (472L/hh/d). Householders included in the Ipswich sample were clearly the most conservative water consumers, using an average of 111L/p/d (305L/hh/d). In general, there was less variation in total household use in Ipswich than in the other regions. For example, the standard deviation was 46L/p/d for Ipswich, which is low when compared with the average standard deviation for the other regions of 90L/p/d (data not shown). This is unexpected given the smaller sample size for Ipswich, and may suggest that water conservation and water use awareness is more uniform across all family types and socio-demographic groups in this region. This may also partly explain the low overall water use compared to the other regions. (Further examination of water use patterns and socio-demographics in future reports will Figure 4: Household per capita consumption (L/p/d) activity breakdown for each participant in the SEQREUS study. Figure 5: Per capita end use breakdown for SEQ regions.
Water Journal April 2011