4.2B Water supply Notes

Water Demand and Population Growth

1. Each person requires water for basic domestic needs such as drinking, cooking, cleaning, and sanitation.
2. The World Health Organization (WHO) estimates that each person needs 50-100 liters of water per day for essential domestic use.
3. As population increases, total water demand rises proportionally, especially in rapidly growing regions of Africa and South Asia.
4. Urbanization exacerbates demand because cities require large-scale supply systems, sewage treatment, and infrastructure expansion.

Economic Development and Rising Consumption

1. High-income countries (HICs): Use large quantities for domestic comfort — gardening, car washing, pools, and sanitation.
2. Middle-income countries (MICs): Show the fastest increase in water demand due to expanding industries and mechanized agriculture.
3. Low-income countries (LICs): Depend mainly on agricultural use but face challenges in access and sanitation infrastructure.

Human Use of Water

1. Human societies rely on water for domestic, agricultural, industrial, and energy purposes, and as populations grow or economies expand, the demand for freshwater increases dramatically.
2. Sustainable management of this resource becomes vital to balance human needs with environmental conservation.

Domestic Water Use

1. Domestic water use includes drinking, cooking, washing, cleaning, and sanitation.
2. The World Health Organization (WHO) recommends 50–100 liters per person per day to meet basic needs.
3. Urban households often consume more water due to piped supplies, washing machines, and gardens, whereas rural communities rely more on manual collection and conservation practices.
4. In developing nations, access is often limited.
5. Many families spend hours collecting water daily, often from unsafe sources.

Agricultural Water Use

1. Agriculture remains the largest global water user, accounting for about 70% of total withdrawals.
2. Irrigation significantly increases crop yields but also drives water depletion.
3. Livestock farming uses more water than crop farming due to animal drinking, feed production, and cleaning facilities.
4. Modern irrigation systems (sprinkler, drip irrigation) improve efficiency but require investment.

Industrial Water Use

1. Industry accounts for about 20% of global water use, though this varies by region.
2. Water is used for cooling machinery, cleaning, processing materials, and generating hydroelectric power.
3. Heavy industries (steel, chemical, textile) require vast quantities of water, while light manufacturing uses less.
4. Industrial water use increases rapidly as economies shift from agriculture to manufacturing.

Strategies to Meet Growing Water Demands

Increase the Water Supply

1. Extracting from new sources: deeper aquifers, rivers, or desalination.
2. Building dams and reservoirs to store and regulate water.
3. Transferring water between basins (inter-basin transfers).
4. Importing water through trade or shared agreements.

Increase the Efficiency of Water Use

1. Use low-flow taps and toilets, water-efficient appliances, and greywater recycling in homes.
2. Adopt drip or sprinkler irrigation instead of flood irrigation.