Demand Forecast

6, 20 & 50 Year Demand Projections
Future water demands are estimated based on historical demands plus the demand from an additional 40 new equivalent residential units (ERUs) per year. Demand estimates for new ERUs are as follows:
  • Average Day Demand: 670 gallons per day/ERU
  • Peak Day Demand: 1,800 gallons per day/ERU
  • Peak Hour Demand: 3,600 gallons per day/ERU
In estimating future demands, it is assumed that separate irrigation will not be available and that the distribution of new connections between the pressure zones will be similar to what has occurred in the past. Actual demands will vary depending on the progress of developments that are being proposed.

Water Demand Forecast - Table 3-15
Table 3-15 includes a water demand forecast for the system and Pressure Zone 3. A separate forecast is not included for Zone 4 since a significant increase in connections is not expected in this zone in the near future. Before new connections are installed in Zone 4, additional pumping, storage, and distribution system improvements are necessary. The cost of these improvements makes it more likely for the lower zones to develop first. The lower zones include sufficient undeveloped land to accommodate 20-years of growth.

Without Water Savings
Demands without projected water savings from Water Use Efficiency Program are as follows.
  1. System
  2. Zone 3
  3. Zone 4
Classification
2008 2014 2028 2058
Projected Additional ERUs
n/a 240 800 2,000
Average Day Demand (Gallons Per Day)
831,000
992,000 1,367,000 2,171,000
Peak Day Demand (Gallons Per Day)
1,865,000 2,297,000 3,305,000 5,465,000
Peak Hour Demand (Gallons Per Minute)
2,450 3,050 4,450 7,450
With Water Savings
Demands with projected water savings from Water Use Efficiency Program are as follows.
  1. System
  2. Zone 3
  3. Zone 4
Classification 2008 2014 2028 2058
Projected Additional ERUs
n/a 240 800 2,000
Average Day Demand (Gallons Per Day)
831,000 962,000 1,326,000 2,100,000
Peak Day Demand (Gallons Per Day)
1,865,000 2,228,000 3,206,000 5,300,0000
Peak Hour Demand (Gallons Per Minute)
2,450 2,960 4,320 7,230
Notes
  • Number of customers and demands for Zone 3 include all zones except Zone 1 and 1a.
  • Water demand forecasts are based on the highest recorded average day, peak day, and peak hour demands through 2008, plus demand projections for future single-family residential customers without separate irrigation.
  • Development of Zone 4 is likely within the next 50 years, and possibly within the next 20 years. To what extent is difficult to predict.
  • Demands without projected water savings from water use efficiency program will be used in the system analysis.
Demands Per Acre
Single-family demand projections per acre are listed below. The projections are based on 3.5 units per acre, which is similar to Terraced Estates (423 units per 120 acres) and Mount Adams Estates (79 units per 22 acres).

Time Without Separate Irrigation With Separate Irrigation
Average Day Demand 2,350 gallons per day per acre, or 2.6 acre-feet per acre per year 1,330 gallons per day per acre, or 1.5 acre-feet per acre per year
Peak Day Demand 6,300 gallons per day per acre, or 4.4 gallons per minute per acre 2,450 gallons per day per acre, or 1.7 gallons per minute per acre