Water demand & its types

Water is an essential resource for life and human activities. It is critical not only for survival but also for various economic sectors, including agriculture, industry, and domestic use. The growing population, urbanization, and industrialization have led to an increasing demand for water across the globe. In this blog post, we’ll explore what water demand is, the various types of water demand, the factors influencing it, and a specific focus on water demand in India.

» What is Water Demand?

● Water demand refers to the total amount of water required for various human activities, including domestic, industrial, and agricultural purposes. It encompasses both the quantity and quality of water needed to meet the demands of daily life, production, and environmental requirements.
● Water demand is defined as quantity(volume) of water required by users to satisfy their needs.
● At home water is required for daily needs such as cooking, drinking, bathing, cleaning, laundry etc.
● At institution, parks and market area water is needed for watering of public parks or gardens, public fountains, sprinkling and road washing etc.
● Water is required for firefighting & to compensate the water losses also.
● Estimation of water demand is necessary as on the basis of estimated water demand the water supply scheme is to be designed.
● Under-estimation leads to inadequate design whereas over estimation results in uneconomical and inefficient water supply system.

» Per Capita Demand (q) -

● Per capita water demand refers to the average amount of water used by a person per day. 
● It includes the domestic use, industrial and commercial use, public use, wastes, thefts etc.
● It is typically measured in liters per capita per day (LPCD) and varies based on factors such as lifestyle, climate, and economic status. 
● For instance, in developed nations, the per capita water demand is often higher due to greater access to water for various purposes, while in developing countries, this demand may be lower.

Per Capita Demand (q) in litres per day per head = Total Yearly water req. per day per head / 365 x Design population 

» Types of Water Demand -

Water demand can be classified into different categories based on the purpose for which water is used. These categories include:

1. Domestic Water Demand
2. Industrial Water Demand
3. Commercial and Institutional Water Demand
4. Demand for public uses
5. Fire demand

1. Domestic Water Demand -

● Domestic water demand refers to the water required for personal household consumption, including drinking, bathing, cooking, cleaning, and sanitation. 
● This type of demand is influenced by factors such as the size of households, standard of living, and regional water availability. In urban areas, where the population is dense, the domestic water demand tends to be higher due to greater access to water for multiple uses.
● GOI manual lays down a limit on water consumption between 135 to 225 LPCD.
● As per IS:1172 - 1993, domestic water demand for a town or city with a full flushing system is typically considered to be 200 liters per capita per day (lpcd), but this can be reduced to 135 lpcd for Lower Income Groups (LIG) and Economically Weaker Section of Society (EWS).

2. Industrial Water Demand -

● Industrial water demand refers to the water required for industrial processes, cooling, and cleaning. Industries such as manufacturing, energy production, and food processing are among the largest consumers of water. 
● As per IS 1172: 1993, the industrial water demand per capita per day is usually calculated based on the scale and nature of industrial operations.
● The ordinary per capita consumption for industrial cities is generally taken as 50 LPCD.
For high industrial cities this demand may be taken as 450 LPCD.

3. Commercial and Institutional Water Demand -

● The water requirements of institutions, such as hospitals, hotels, restaurants, schools and colleges, railway stations, offices etc.
● On an average, a per capita demand of 20 liters/head/day is usually considered to be enough to meet Commercial and Institutional Demands.

As per IS: 1172 - 1963, water supply requirements for the public buildings other than residences are as follows:

S. No.	Type of Building	Consumption per Capita per Day (litres)
1.	Factories where bathrooms are required	45
2.	Hospital per bed No. of beds exceeding 100	450
3.	Hostels	135
4.	Office	45
5.	Hotel (per bed)	180
6.	Cinema concert halls and theatres (per seat)	15
7.	Boarding schools	135
8.	Garden, sport grounds (per sq. m)	35
9.	Animal/vehicles	45

4. Demand for public uses -

● This includes water requirement for parks, washing of roads, public drinking, gardening etc.
● A nominal amount net exceeding 5% of the total consumption of city is provided as demand for public use.
● For public use, 10 LPCD is considered.

5. Fire demand -

● Water required for firefighting is usually known as fire demand.
● For fire demand, water requirement is 1 LPCD.
● It is a function of population and may be computed from rational formulae.

» Factors Affecting Water Demand -

Several factors influence the water demand in any given region, including:

1. Population Growth: An increase in population leads to a higher demand for water, both for domestic and agricultural purposes.

2. Economic Development: Economic growth leads to increased industrialization and urbanization, both of which elevate water consumption.

3. Climate and Weather: Hotter climates generally require more water for cooling purposes, agriculture, and personal consumption.

4. Cultural and Lifestyle Factors: Cultural practices and lifestyle choices, such as the use of water for religious or ceremonial purposes, can influence water demand.

5. Technological Advances: The adoption of water-efficient technologies and practices can help reduce water demand, especially in industrial and agricultural sectors.

6. Water Pricing and Policies: Water availability and demand can be significantly influenced by government policies, water tariffs, and resource allocation strategies.