Variables
Description
What is this formula?
Water Demand Forecast estimates future water demand based on current demand, expected growth rate, and forecast horizon.
It is one of the most widely used planning tools in water resource engineering, municipal infrastructure design, and urban development projects.
The formula applies compound growth principles similar to those used in population and economic forecasting.
When to use it
Use this formula when evaluating:
- Municipal water supply systems
- Urban growth planning
- Reservoir sizing studies
- Water treatment plant expansion
- Long-term infrastructure projects
- Regional water resource management
Example
A city currently consumes 120,000 m³/day of water.
Engineers estimate annual demand growth of 2.5%.
Forecast period:
10 years
Data:
WD0 = 120,000 m³/day
r = 0.025
t = 10 years
Formula:
WDf = WD0 × (1 + r)^t
Substitution:
WDf = 120,000 × (1.025)^10
WDf = 120,000 × 1.2801
Result:
WDf = 153,612 m³/day
The projected water demand after 10 years is approximately 153,612 m³/day.
Applications
- Water utility planning
- Reservoir development
- Pipeline sizing
- Treatment plant design
- Regional planning
- Infrastructure investment studies
Note
This model assumes a constant annual growth rate throughout the forecast period. Real-world water demand may be influenced by population changes, industrial development, climate variability, conservation programs, economic conditions, regulations, and technological improvements. More advanced forecasting methods may incorporate these factors explicitly.