Understanding the various components of water demand is crucial when designing water works for a city. Total water demand for a city is typically divided into several categories, each contributing a specific percentage to the overall requirement.

Components of Total Water Demand

The total water demand for a city can be broadly categorized as follows:

• Domestic Water Demand: Water used for household purposes like drinking, cooking, bathing, flushing, etc.
• Commercial and Industrial Water Demand: Water required by shops, offices, businesses, factories, etc.
• Public Use Water Demand: Water used for public purposes such as watering parks and gardens, street washing, public fountains, schools, hospitals, libraries, and municipal buildings.
• Fire Demand: Water required for extinguishing fires.
• Losses and Waste: Water lost due to leakage in pipes, unauthorized connections, faulty meters, etc.

Public Use Water Demand Percentage

When designing a water supply system for a city, the water demand for public use is an important consideration. This category covers essential services that benefit the community as a whole. The percentage of total water demand allocated for public use can vary slightly depending on the specific city and design standards, but a common and widely accepted value is considered for planning purposes.

Based on typical municipal water supply design standards, the water demand for public use is generally estimated as a small percentage of the total daily water demand. This percentage accounts for the various public facilities and services mentioned earlier.

Common design practice suggests that the allowance for public use water demand is kept around 5% of the total water consumption or total demand.

Evaluating the Options

Let's compare this typical value with the given options:

• Option 1: 15%
• Option 2: 10%
• Option 3: 25%
• Option 4: 5%

Comparing the standard percentage for public use water demand (5%) with the given options, we find that Option 4 matches this value.

Therefore, the water demand for public use, as compared to total demand, typically kept in the design of water works for a city is 5%.