Topic explanation

Standard explanation

Water is an essential natural resource required for life, agriculture, sanitation, industry, energy production and the functioning of ecosystems.

Key points

• Beginner: There is a lot of water on Earth, but most of it is salty. Only a smaller amount is freshwater that
• Intermediate: Water-resource management considers both quantity and quality. A river may hold much water but still
• Most Earth water is saline; readily available freshwater is limited.
• Water availability depends on both quantity and quality.
• Pollution and excessive withdrawal reduce usable supplies.

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