Water Usage and Demand Quiz

Study Notes

Water is used for domestic, public, industrial, agricultural, power production, and carrying away waste.
Domestic water demand comprises water used in private buildings for cooking, washing, bathing, gardening, and sanitation, accounting for 50-60% of total water consumption.
Industrial water demand encompasses water used in factories, offices, hotels, hospitals, etc., representing 20-25% of total water demand.
Public demand includes water utilized for watering public parks, gardening, road sprinkling, and public fountains, typically amounting to 5% of total demand.
Fire demand refers to the quantity of water needed to extinguish fires, with the amount calculated using empirical formulae.

National Board of Underwriters formula: Q = 1020 √ p (1 – 0.01 √p) (US units) or Q= 64 √p (1 -0.01 √ p ) in litre per sec (metric units)
Freeman's formula: Q = 1136.5 { p ― + 10 } (US gallons per minute) where p = population in thousands 10
Fire demand is a substantial quantity required only occasionally for short periods.

Water loss occurs due to leakage at joints and fittings, and unauthorized connections.
Losses can be reduced through proper fittings, inspections, and investigations.
Per capita demand is the annual average daily water requirement per person, encompassing domestic, industrial, public, and water loss, calculated as Q/ P×365 (litres per day) where Q = total water required by a city per year (litres) and P = city population.

Summer sees the highest demand due to increased water usage for bathing, cooling, lawn watering, and street sprinkling.
This fluctuation can reach 150% of average annual consumption.

Daily demand varies due to consumer habits, climatic conditions, and holidays (e.g., increased demand during festivals or fairs).
Peak daily consumption can be as high as 180% of average annual consumption.

Hourly demand is not uniform, with peak hours reaching 200% of average daily demand.

Arithmetical increase method: Assumes a constant increase, calculating the average increase over recent decades to project future population (Pn = p+ n x i where p = present population and I = yearly/decade increase).
Geometrical increase method: Bases forecasting on a constant percentage growth rate (Pn = p{ 1+ i } n where I= yearly/decade increase).
Incremental increase method: Improves on the arithmetical increase method by adding the average net incremental increase for each future decade.
Changing rate of increase method: Uses a changing, decreasing growth rate for large, developed cities.
Graphical method: Plots population data from recent decades on a graph and extrapolates a trend line to estimate future population.
Comparative method: Forecasts population by comparing the city in question to similar cities with known population trends.

The total water requirement for a town considers domestic, industrial, public, and other needs.
A 30-40% allowance is added for wastage.
Total requirements vary depending on factors such as climatic conditions, people’s habits, industry, cost of water, and more.