It is necessary to determine the quantity of water required daily before designing a water supply scheme. The first step is to determine the demand for the town, village, etc and to find suitable sources of water from which water demand should meet. Types of water demand are briefly explained below.
Types of Water Demand
Seven types of water demand are :
a. Domestic Demand
The quantity of water required in the houses for drinking, bathing, cooking, toilet flushing, gardening, individual air-condition, etc is called domestic demand.
For designing purpose in developing countries, we use the data as follow:
By public tap / No private connection – 45 lpcd( litre per capita per day)
For partially plumbed house – 65 lpcd(litre per capita per day)
For fully plumbed houses – 110 lpcd(litre per capita per day)
In developed countries; houses are fully plumbed and about 300 litre per capita per day is usually taken.
b. Livestock Demand
The quantity of water required for the domestic animal is known as livestock demand.
Where livestock demand is not considered?
Livestock demand is not considered in the urban area but we considered it in rural areas as livestock is an important component of the rural economy.
” Livestock demand must be more than 20% of the designed domestic demand.”
For Big Animals –cows, buffalo, horse – 45 L/(animal day)
For Medium Animals – sheep, goat – 20 L/(animal day)
For Birds– parrots, ducks, hen – 20 L/ (100 bird day)
c. Commercial and Institutional Demand
It includes the demand for offices, stores, schools, hospital, theatres, etc.
a. Educational Institution
Day School – 10 lpcd( litre per capita per day)
Hostels – 65 lpcd( litre per capita per day)
With Bed – 500 litre per bed per day
Without Bed- 2500 litre per day
With Bed – 200 litre per bed per day
Without Bed – 500-1500 litre per day
d. Industry Demand
It is commonly considered in urban areas. Quality of water required for the various industry is known as industry demand. Normally 20-25% of total demand is taken as industry demand.
e. Demand for public places or Municipal demand
It includes water required for washing and sprinkling on road, cleaning sewers, watering public parks, etc. Normally 5% of total demand is taken as municipal demand for public places.
f. Fire Demand
During the breakout of the fire, water is used for fire fighting is called fire demand.
g. Losses and Wastes
Water losses and wastes may be because of the following:
a. Leakage and overflow from services reservoir.
b. Losses due to the defective pipe.
c. Losses that are due to the unauthorized or illegal connection.
d. Losses from the consumer when they keep on taps of public tap stand even when they are not using the water.
e. About 15% of water demand is taken to compensate for losses, theft and waste of water.
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