Water Supply Design Tool

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Demand Estimation

Daily & peak water demand

Population & Usage

Population Served persons

Per Capita Demand L/person/day

Zone Type

Design Factors

Peak Factor (pf)

Hourly Peak Factor

Fire Demand kL/day

Design Period years

Annual Population Growth Rate %

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Enter population data

Fill in the demand parameters and click Calculate.

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Reference Formulas

IS 1172 · CPHEEO Guidelines

Daily Demand

ADD = Population × Per Capita Demand
Peak Day Demand = ADD × Peak Factor
Peak Hour Demand = ADD × Hourly Peak Factor / 24

Future Population

Pf = P₀ × (1 + r/100)ⁿ
where r = growth rate, n = design period

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Pipe Sizing

Hazen-Williams pressure loss

Flow & Pipe Parameters

Design Flow Rate L/s

Pipe Diameter mm

Pipe Length m

Pipe Material / C Value

Pressure Requirements

Inlet Pressure m

Min Residual Pressure m

Minor Losses Factor (K)

Fraction of major losses (fittings, bends, valves)

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Enter pipe data

Fill in flow and pipe parameters and click Size the Pipe.

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Hazen-Williams Formula

Pressure drop calculation

Hazen-Williams Equation

V = 0.8492 · C · R^0.63 · S^0.54
where R = hydraulic radius (D/4), S = slope
Q = V × A

Head Loss

hf = 10.67 · L · Q^1.852 / (C^1.852 · D^4.87)
Q in m³/s, D in m, L in m

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Reservoir Capacity

Storage & balancing capacity

Supply & Demand Data

Average Daily Demand kL/day

Supply Hours/Day hrs

Peak Hour Demand kL/hr

Additional Requirements

Fire Fighting Reserve kL

Emergency Reserve %

Freeboard Allowance m

Tank Plan Dimension L m

Tank Plan Dimension W m

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Enter supply data

Fill in demand and supply data to size the reservoir.

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Capacity Guidelines

CPHEEO Manual on Water Supply

Balancing Storage

Required to balance hourly variation when
supply rate ≠ demand rate over the day.
Typically 15–30% of ADD.

Total Storage

= Balancing Storage
+ Fire Fighting Reserve
+ Emergency Reserve
+ Freeboard volume