1. Table (2.1): Water Consumption for Various Purposes:
Types of Consumption
Normal Range (lit/capita/day)
Average
% of total 1
Domestic Consumption
65-300
160 35 2
Industrial and Commercial Demand
45-450
135 30 3
Public Uses including Fire Demand
20-90 45 10 4
Losses and Waste
45-150 62 25

2. Factors affecting per capita demand:
1) Size of the city: Per capita demand for big cities is generally large as compared to that for smaller towns as big cities have sewered houses.
2) Presence of industries.
3) Climatic conditions.
4) Habits of people and their economic status.
5) Quality of water: If water is aesthetically and medically safe, the consumption will increase as people will not resort to private wells, etc.
6) Pressure in the distribution system.
7) Efficiency of water works administration: Leaks in water mains and services; and unauthorised use of water can be kept to a minimum by surveys.
8) Cost of water.

3. 2.3.1 Fluctuations in Rate of Demand
Average Daily Per Capita Demand = Quantity Required in 12 Months/ (365 x Population).
If this average demand is supplied at all the times, it will not be sufficient to meet the fluctuations.
Seasonal variation: The demand peaks during summer. Fire breakouts are generally more in summer, increasing demand. So, there is seasonal variation .
Daily variation depends on the activity. People draw out more water on Sundays and Festival days, thus increasing demand on these days.
Hourly variations are very important as they have a wide range. During active household working hours i.e. from six to ten in the morning and four to eight in the evening, the bulk of the daily requirement is taken. During other hours the requirement is negligible. Moreover, if a fire breaks out, a huge quantity of water is required to be supplied during short duration, necessitating the need for a maximum rate of hourly supply.

5. 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
To estimate the ratios of maximum month, week, day and hour demand it can be used the following equation:
P=180 t-0.1 ………………..2.1
Where P= percent of the annual average demand for time, t.
t=time, day. From 2hrs to 365 day

6. 2.4 Fire Fighting Demand
The per capita fire demand is very less on an average basis but the rate at which the water is required is very large. The rate of fire demand is sometimes treated as a function of population and is worked out from following empirical formula:
Where
F= fire flow required m3/day
A= total area m2
C= coefficient related to the type of construction:
1.5 for wood frame construction
1 for ordinary construction
0.8 for noncombustible construction
0.6 for fire resistive construction

7. Note
If a building consists from many materials, for example 2 materials. In this case we must calculate the total area A=A1+A2, and we consider that all building consist from the first material and we find F1. In the next step we consider that all building consist from the second material and we find F2. Finally, fire flow required equal:
F=F1*(A1/A)+F2*(A2/A) …………..2.3 ,the following table shows the duration for fire flow:

8. Table (2.2) : Fire flow duration
Flow rate m3/min
Duration, h
7.6 2
11.3 3
15.1 4
18.9 5
22.7 6
26.5 7
30.2 8 34 9
37.8 10