Municipal Water Demand Forecaster
Master Planning & System Sizing
Design Year 0000
Future Population
0
Avg Daily Demand (ADD)
Base Production Rate 0.0 MLD
Base Production Rate 0.0 MLD
Max Daily Demand (MDD)
Plant/Reservoir Design Flow 0.0 MLD
Plant/Reservoir Design Flow 0.0 MLD
Peak Hourly Demand (PHD)
Network/Pump Design Flow 0.0 MLD
Network/Pump Design Flow 0.0 MLD
Infrastructure Capacity Scaling (Design Year Breakdown)
Visualizing the impact of NRW and Peaking Factors on system sizing.
Projection Curves: Population & Demand Growth
Year-by-Year Projection Table
| Year | Projected Population | Net Demand (MLD) | Avg Daily Demand (ADD) (MLD) | Max Daily Demand (MDD) (MLD) | Peak Hour (PHD) (L/s) |
|---|
Master Planning Methodology
1. Geometric Population Growth
Populations typically compound over time. The future population ($P_n$) is calculated from the base population ($P_0$) over $n$ years at an annual growth rate ($r$).
$$P_n = P_0 \times (1 + r)^n$$
2. Average Daily Demand (ADD)
The baseline water produced by the treatment plant over a year. It equals the net consumption (Population $\times$ per capita demand $q$) scaled up to account for Non-Revenue Water ($NRW$) like leaks and unbilled usage.
$$ADD = \frac{P_n \times q}{1 - NRW}$$
3. Peaking Factors & Infrastructure Sizing
Water is not consumed evenly. People use more water in the summer (Max Day) and significantly more water in the morning/evening (Peak Hour).
- Maximum Daily Demand (MDD): $MDD = ADD \times MDF$. Used to size Water Treatment Plants, Intake Pumps, and strategic Storage Reservoirs.
- Peak Hourly Demand (PHD): $PHD = ADD \times PHF$. Used to size the internal distribution pipe network and booster pump stations to ensure pressure doesn't drop when everyone turns on their tap simultaneously.
4. Typical Per Capita Demand
| Development Type | Demand (Lpcd) | Demand (Gpcd) |
|---|---|---|
| Rural / Small Town | 80 - 120 | 20 - 30 |
| Suburban / Residential | 150 - 200 | 40 - 50 |
| Urban / City Center | 200 - 300 | 50 - 80 |
| Highly Developed / Industrial | 300+ | 80+ |
5. Typical Peaking Factors
| Factor | Typical Range | Used For Sizing |
|---|---|---|
| Max Day Factor (MDF) | 1.5 - 2.5 | Treatment Plants, Reservoirs |
| Peak Hour Factor (PHF) | 2.5 - 4.0 | Distribution Mains, Pumps |
| Min Hour Factor | 0.2 - 0.4 | Pump Cycling, Night Pressure |
References
- American Water Works Association (AWWA) & American Society of Civil Engineers (ASCE). (2012). Water Treatment Plant Design (5th ed.). McGraw-Hill Education. Google Scholar
- Mays, L. W. (2010). Water Resources Engineering (2nd ed.). John Wiley & Sons. Google Scholar
- Viessman, W., Hammer, M. J., Perez, E. M., & Chadik, P. A. (2009). Water Supply and Pollution Control (8th ed.). Pearson. Google Scholar
- World Health Organization (WHO). (2003). Domestic Water Quantity, Service Level and Health. WHO IRIS
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