JNTU B.Tech III WATER SUPPLY ENGINEERING Previous Question Paper (October - 2020 - R16)

Water demand in a community is categorized based on the purpose of usage, which is essential for designing water supply schemes, treatment plants, and distribution systems. The total water requirement is the sum of several distinct types of demand:

1. Domestic Water Demand: This includes water required for drinking, cooking, bathing, washing clothes, and flushing toilets. The per capita consumption typically ranges from 135 to 225 liters per day per person, depending on the standard of living and availability of water.
2. Industrial Water Demand: This is the water required for manufacturing processes, cooling, and boiler feed in industries. The demand varies significantly based on the type of industry (e.g., paper mills, textile mills, or refineries) and is often estimated based on the unit of production.
3. Institutional and Commercial Demand: This covers water usage in schools, hospitals, offices, hotels, and shopping malls. Requirements are calculated based on the number of occupants or beds in hospitals, and the nature of the commercial activity.
4. Public Use Demand: This includes water for public parks, street washing, cleaning of public sewers, and ornamental fountains. It usually accounts for about 5% of the total water demand.
5. Fire Demand: This is the water stored and kept available for firefighting purposes. It is calculated using empirical formulas like Kuichling's formula or Freeman's formula, which relate the required flow rate to the population of the city.
6. Water Losses and Thefts: Due to pipe leaks, faulty meters, and unauthorized connections, a portion of the water supplied is lost. In well-maintained systems, this is typically limited to 10-15% of the total supply.

To determine the total design capacity, these demands are aggregated, and a factor of safety is applied to account for seasonal and hourly fluctuations in demand, ensuring the system can handle peak flow conditions.