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<br />I <br />I <br />1 <br />l <br />I <br />I <br />\ <br />I <br />I <br />I <br />I <br /> <br />I <br />I <br />I <br />I <br />J <br />-i <br />1 <br />I <br />I <br /> <br />3-5 <br /> <br />Water Demand and Wastewater Flow Projections <br /> <br />New water demand and wastewater flow projections have been based on an analysis of <br />the past 4 years of data. From this analysis, monthly use factors have been developed in tenus <br />of single family equivalent (SFE) taps. The District measures tap accumulation for all customer <br />classifications as 3/4-inch equivalents (SFEs). <br /> <br />Projection curves have been developed based on the data tabulated in Appendix B. These <br />curves, shown as Figures 3-6 through 3-9, depict three potential growth scenarios defmed as: <br /> <br />· Low growth - an increase of 800 SPEs per year <br />· Moderate growth- an increase of 1,000 SFEs per year <br />· High growth - an increase of 1,200 SFEs per year <br /> <br />These projections should be updated every 2 to 3 years to account for changing <br />development trends, water use characteristics, and other variables. Recent trends toward higher <br />growth in SFEs per year will be closely monitored to detennine if projection levels need to be. <br />increased. By using an SFE-based 4- to 5-year running average of water consumption, relatively <br />accurate projections can be developed. The use of a running average has the advantage of <br />averaging out the effects of variables such as weather. In addition, as the District implements <br />its conservation program, demand patterns will change over time. In the event of dramatic <br />changes to water use patterns, specific corrections may be necessary. <br /> <br />The District has a metering and billing system capable of sorting customer classes and <br />sub-sorting within particular classes. These features will be very helpful in developing base <br />demand data and analyzing the effects of conservation measures on the various customer classes. <br /> <br />Forecasting Residential Water Use <br /> <br />Table 3-3 -sliows deteiniliiariti known-tO IDfluence residential -demand. . Several of these <br />detenuinants can influence short-run demand, while others have long-run effects. <br /> <br />Table 3-3 Typical Determinants of Residential Water Use' <br /> <br />Long-run demand response variables Short-run demand response variables <br />Standard of living Household income <br />Persons per household Waw. price <br />Housing type Rate Stmclure <br />Irrigable landscape area Conservation practices <br />Water-using appliances Precipitation <br />Plumbing fixtures Air temperature <br />Swimming pools Evapotranspiration rate <br />Evaporative coolers <br /> <br />'Evaluating Urban Water Conservation Programs: A Procedures Manual, prepared for California urban water <br />agencies by Planning & Management Consultants, Ud., February 1992. <br /> <br />21-6657 <br />