WATER DEMAND

 WATER DEMAND 

Water demand is the estimation of planning a water supply scheme in any town or city or anything to desire. About 80% of water consume in Agriculture sector rest is use in domestic, industrial and other public demand purpose.

TYPES OF WATER DEMAND 

Domestic Water Demand :- 

It is generally includes the required of water for privet building, cooking, bathing, washing etc. Actually it is depends on living standard of the consumer.

• About 50-60% Water is consume of the total water consumption and it is about nearly 135 to 225 lpcd as per IS code.
• Minimum water demand for full flushing system in ordinary condition is 200 lpcd and it is includes in HIG(High Income Group) and 135 lpcd for LIG(Low Income Group).

Industrial Water Demand :-

 Industrial water requirement depend upon the type and number of industry present in the town. It is as high as 450 lpcd to 50 lpcd. 

Table 1.1

Table 1.2

 

Demand for Public Uses:-

It is including gardening, washing of roads parks etc. Generally not exceeding 5% of total consumption.

Fire Demand:-

If the population is 50 lakhs, the fire demand is nearly to 1 lpcd and it should be easily availability. There are few requirement are to be follow 

• The minimum water Pressure should be provide about 100 to 150 KN/㎡ and maintained for 4 to 5 hours of constant use of fire hydrant.
• The number of fire jets required by this formula F=2.8√P and it is depend on size population.
• Discharge should be nearly 1100 l/min.

Losses of Water by Thefts and Wastes:-

Generally losses of water are include in theft , unauthorised water connection, leackage in piping system etc. It is nearly 15% of total water consumption which is about 55 lpcd for this purpose we are provide.

CALCULATION FOR FIRE DEMAND

There are various formula are given, from this formula we can get the fire demand.

• For population exceeding 50,000 the fire demand is   

Kuchling's  Formula

Freeman's  Formula 

Buston's Formula

Q= Amount of water required in litre/min

P= Population in thousands 

TOTAL MAXIMUM WATER DEMAND 

 Total maximum water demand is the sum of all demand which is nearly equal to 335 lpcd.

PER CAPITA DEMAND (q)

FACTORS AFFECTING PER CAPITA DEMAND

1.Size of the city 

2.Climatic Condition

3.Types of Gentry and Habits of people 

4.Indutrial and Commercial Activties

5.Development of sewerage facilities 

6.Quality of the Water supply 

7.Cost of water and charging method 

8. System of supply 

9.Pressure Distribution System

VARIATION OF DEMAND 

 Maximum daily demand = 1.8 x Average Daily demand =1.8q

Maximum Hourly demand = 1.5 x Average hourly consumption of maximum daily demand 

                                            =1.5x(maximum daily demand/24)=1.5x(1.8 x q/24)=2.7(q/24)

Maximum weekly Demand =1.48 x Average weekly 

Maximum monthly Demand = 1.28 x Average monthly 

DESIGN PERIOD WATER SUPPLY UNIT 

** Coincident draft:- The total draft is taken as the sum of Maximum daily demand and Fire Demand or the Maximum hourly demand whichever is Maximum.