DIFFERENT TYPE OF WATER DEMAND AND PER CAPITA DEMAND

The water demand of any city can be classified into following categories:

1.Domestic Water Demand

• Water required for domestic purposes such as washing, drinking, cooking, gardening, etc.
• GOI manual consider Domestic water usage limit between 135 LPCD to 225 (Litre Per Capita per Day).
• For a town with full flushing system, the minimum domestic water requirement should be taken as 200 LPCD under ordinary conditions. 
• For low income groups, we can reduce demand limit upto 135 litres per capita per day.

2.Commercial/ Institutional Water Demand

• On an average, 20 LPCD is usually considered as  per capita demand to meet commercial and institutional demands. But this value can go up to 50 LPCD for highly commercialized cities, 
• For Cinemas and theatres, demand is approx. 15 LPCD and for hospitals, demand is maximum (340 to 380 LPCD).

3.Industrial Water Demand

• The industrial water demand represents the water demand of any industries which are existing or likely to be started in future.
• For paper industries, for 1 tonne of paper production, 200-400 Litres of water is used.
• For petroleum refinery and sugar mills, per tonne production needs 1-2 litres of water.

4.Demand for Public Use

• This includes water requirement for Parks, sprinkling on roads , public drinking, public toilets etc.
• The amount not exceeding 5% of the total consumption of city can be considered as demand for public use.

5.Fire Demand

Following requirements must be met for Fire Demand:

• Three jet stream are simultaneously thrown from each hydrant, one on the burning property and one on each adjacent property.
• Discharge in each stream should not be less than 1100 L/min.
• The minimum head available should be 12 to 15 metre and should be maintained for 4 to 5 hours
• For a city of 50 Lakhs population, the total amount of water consumption amounts to 1 LPCD hardly, but this water should be easily available and kept always stored in service reservoirs

Kuichling's Formula for Fire Demand

6.Losses and Thefts

• Water lost in leakage due to bad plumbing, theft, unauthorized water connections and other losses.
• This amount is taken as 15% of total demand.

PER CAPITA Demand

It is annual AVERAGE amount of Daily water required by 1 person and includes domestic, industrial, commercial, public use, thefts, etc.

Factors Affecting Per capita demand:

• Size of city
• Climatic Condition
• Quality of water supply
• Pressure in distribution system
• System of Supply

Various Type of Demand for Design

Also Read:

• Water Demand and Population Forecasting Method 
• Municipal Solid Waste Management