DOMESTIC WATER REQUIRMENTS FOR URBAN AND RURAL AREAS.

1. Domestic purposes

2. Civic or public purposes

3. Industrial purposes

4. Business or trade purposes

5. Loss and waste

Domestic purposes ; 

The quantity of water required for domestic purposes can be sub divided as follows:

1. Drinking

A human body contains about 70 % of water. The consumption of water by a man is required for various physiological processes such as blood formation, food assimilation, etc.

The quantity of water which a man would require for drinking depends on various factors.  But on the average and under normal conditions, it is about  2 litres per day.

2. Cooking

Some quantity of water will also be required for cooking.  The quantity of water required for this purpose will depend upon the stage of advancement of the family in particular and society in general. 

 However, for the purpose of estimation, amount of water required for cooking may be assumed as about 5 litres per capita per day.

3. Bathing

The quantity of water required for bathing purpose will mainly depend on the habits of people and type of climate. 

 For an Indian bath, this quantity may be assumed as about 30 to 40 litres per capita per day and for tub-bath, it may be taken as about 50 to 80 litres per capita per day.

4. Washing hands, face etc.

The quantity of water required for this purpose will depend on the habits of people and may roughly be taken as 5 to 10 litres capita per day.

5. Household sanitary purposes

Under this division, the water is required for washing clothes, floors, utensils, etc. and it may be assumed to be about 50 to 60 litres per capita per day.

6. Private gardening and irrigation

In case of developed cities, there will be practically no demand of water for this purpose.  In case of undeveloped cities, private wells are generally used to provide water for private gardening and irrigation. 

 It is therefore not essential to include the quantity of water required for this purpose in case of public water supply project.

7. Domestic animals and private vehicles

The amount of water required for the use of domestic animals and private vehicles is not of much concern to a water supply engineer. 

 With the growth and development of town, the cattle disappear and commercial stables come into existence.  The water required for animal drinking and cleaning of stables is around 13.5 litres per capita per day.

The requirement of water for domestic purposes is a minimum of 135 litres per capita per day which amounts to 50 %  of the total water requirements per capita per day.

Civic or public purposes ;

The quantity of water required for civic or public purposes can be sub divided as follows:

1. Road washing

The roads with heavy amount of dust are to be sprinkled with water to avoid inconvenience to the users. On the average, the quantity of water required for this purpose may be taken as about 5 litres per capita per day.

2. Sanitation purposes

In this division, water is required for cleaning public sanitary blocks, large markets, etc. and for carrying liquid wastes from houses.  The quantity of water required for this purpose will depend on the growth of civilization and may be assumed to be about 2 to 3 litres per capita per day.

3. Ornamental purposes

In order to adorn the town with decorative features, fountains or lakes or ponds are sometimes provided.  These objects require huge quantity of water for their performance.  As far as Indian towns are concerned, the quantity of water required for this purpose may be treated as quite negligible since in most of the towns, the quantity of water available is not enough even with the most urgent needs of the society.

4. Fire demand 

Usually, a fire occurs in factories and stores.  The quantity of wter required for fire fighting purposes should be easily available and always kept stored in the storage reservoir. 

In case of public water supply, fire demand is treated as a function of population and some of the empirical formulae, commonly used for calculating the fire demand are as follows:

Buston’s formula

Q=5663√p

Q = quantity of water required in litres per minute

P = population in thousands

This formula is used in England for moderate provision

John R. Freeman’s formula

 Q = quantity of water required in litres per minute

P = population in thousands

Kuichling’s formula

 Q = quantity of water required in litres per minute

P = population in thousands

National Board of Fire Underwriters  formula

Q = quantity of water required in litres per minute

P = population in thousands

As for Indian conditions are concerned, a moderate allowance of one litre per capita per day for fire demand will be sufficient.

 Industrial purposes ;

The quantity of water required for industrial or commercial purposes can be sub divided as follows:

1. Factories

The quantity of water required for the processes involved in factories will naturally depend on the nature of products, size of factory, etc. and it has no relation with the density of population.  It is quite likely that the demand of water for factories may equal or even exceed the demand of water for domestic purposes.  The possibility of recycling of water in the plant will also have appreciable effect on the demand of water for a particular product.

2. Power stations

A huge quantity of water will be required for working of power stations.  But generally, the power stations are situated away from the cities and they do not represent a serious problem to public water supply.

3. Railways

In most of the cases, the railways make their own arrangements regarding their water requirements and hence, the quantity of water to be consumed by railways is not ordinarily included in any public water supply system.

It is thus not possible to connect the requirement of water for industrial purposes to the population of the city.  It is therefore advisable to study each case independently in this regard and decide the quantity of water required for industrial purposes accordingly.

  For a city with moderate factories, it is estimated that about 20 to 25 per cent of per capita consumption will be required for industrial purposes.

Business or trade purposes ;

Some trades such as dairies, hotels, laundries, motor garages, restaurants, stables, etc. require a large quantity of water.  Such trades are to be maintained in hygienic conditions and sanitation of such places should be strictly insisted.

 The number of such business centres will depend upon the population and for a moderate city, an average value of about 15 to 25 litres per capita per day may be taken as water requirements for this purpose.

Loss and waste ;

The quantity of water required under this category is sometimes termed as unaccounted requirement.

  It includes careless use of water, leakage in mains, valves, other fittings, etc. unauthorized water connections and waste due to other miscellaneous reasons.  

The quantity of water lost due to all these reasons is uncertain and cannot be effectively predicted. However, for the purpose of calculating the average rate of demand it may be estimated to be about 30 to 40 per cent of per capita consumption. 

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