The nationalist writer: The Per Capita Demand and Factor Affecting Per Capita Demand

Water Quantity Estimation

The quantity of water required for municipal uses for which the water supply scheme has to be designed requires following data:

Water consumption rate (Per Capita Demand in litres per day per head)
Population to be served.

Quantity= Per capita demand x Population

The Per Capita Demand (q)

https://youtu.be/qOQjz1IXxwk

It is the annual average amount of daily water required by one person and includes the domestic use, industrial and commercial use, public use, waste, thefts etc.

The Per Capita Demand (q) =

Total yearly water Requirement of the city in liters / (365 x design population)

* Source of Figure S K Garg Water Supply Engineering

Factor Affecting Per Capita Demand

https://youtu.be/qOQjz1IXxwk

per capita demand affected by the following factors:-

Water supply system
Cost of water
Climatic Conditions
Size of the city
Quality of water supply
Pressure in the water distribution system
Metering policy and charging method
Industrial and commercial activities
Development of sewerage facilities

* Source of Figure S K Garg Water Supply Engineering

Fluctuations in Rate of Demand

There are three types of the Fluctuations in Rate of Demand :-

1.Seasonal variation

2.Daily variation

3.Hourly variation

* Source of Figure S K Garg Water Supply Engineering

Maximum daily demand = 1.8 x average daily demand

Maximum hourly demand of maximum day i.e. Peak demand

= 1.5 x average hourly demand
               = 1.5 x Maximum daily demand/24
               = 1.5 x (1.8 x average daily demand)/24
               = 2.7 x average daily demand/24
               = 2.7 x annual average hourly demand

Design Periods:-

The future period for which a provision is made in the water supply scheme is known as the design period.