The Water Supply Lab

Water, but not to spare

Water covers most of the planet, but only a tiny fraction is fresh and usable, and it is spread very unevenly. Some countries have plenty; others face water scarcity. This module looks at how water supply and demand vary around the world, the problems this causes, and how water can be managed sustainably.

The language of water

Four ideas run through the topic:

Who uses the most water?

Globally, which sector uses the most fresh water?

• Agriculture, mainly for irrigating crops
• Domestic use in homes
• Leisure and sport
• Generating electricity for lighting

Water supply terms

Different countries, different problems

Water use and water problems differ with a country's level of development.

The UK's water problems

Select the TWO water problems that the UK faces.

• Water is plentiful in the north and west but most needed in the drier south-east
• Ageing pipes that leak large amounts of water
• Almost no access to any safe drinking water
• Year-round extreme drought across the whole country

Making supplies last

Where water is scarce, technology can help: desalination removes salt from seawater, but it is expensive and uses a lot of energy. Sustainable management makes supplies last. Two contrasting examples: in the developed world, Singapore recycles treated wastewater into clean NEWater; in emerging India, the Wakel River Basin in Rajasthan uses local rainwater harvesting and small dams to store water for the dry season.

Scarcity and where water goes

When demand for water is greater than supply, there is water _____. Globally, most fresh water is used by _____. Making fresh water by removing salt from seawater is called _____. In the developed world, Singapore recycles wastewater into _____, while in Rajasthan, India, local rainwater _____ stores water for the dry season.

Plot the rising demand

This graph shows global water demand rising over time, in billions of cubic metres per decade. Three points are plotted: (1, 20), (2, 30) and (3, 40). Add the point for decade 4, continuing the same straight-line trend.

Manage a water shortage

A hot, dry region faces water shortages. Help decide how to manage its water sustainably.

• The region is on the coast with plenty of energy. What technology could increase its supply?
• Which approach best helps a poorer, inland farming area with seasonal rain?
• How should the different stakeholders be balanced?

What is desalination?

What does desalination do?

• Removes salt from seawater to make it drinkable
• Stores rainwater in a reservoir
• Cleans polluted river water with filters
• Pipes water from a wetter region

Where the fresh water goes

Tap the TWO statements that are correct about water supply and management.

• Agriculture uses the largest share of the world's fresh water.
• Desalination is cheap and uses almost no energy.
• The UK's water problem is partly a supply and demand imbalance between regions.
• Fresh water is spread evenly across the whole world.
• Rainwater harvesting means removing salt from seawater.

Compare the two countries

Compare how a developed country and an emerging or developing country manage water sustainably, using Singapore and the Wakel River Basin in India as examples.

• Describe the water problem each area faces
• Explain how Singapore manages its water, including NEWater
• Explain how the Wakel River Basin manages its water, including rainwater harvesting
• Compare the two approaches, noting cost and technology