Water use by sector
Big idea: Globally, agriculture uses about 70% of all freshwater. Industry uses ~20%, and domestic use is only ~10%. But this varies hugely between countries!
The three main sectors
- Agricultural (~70% globally) — irrigation, livestock, aquaculture
- Industrial (~20% globally) — manufacturing, cooling, processing
- Domestic (~10% globally) — drinking, cooking, sanitation, gardens
Variations between countries
LEDCs (Less Economically Developed)
- Agriculture dominates (up to 90%)
- Less industry
- Lower domestic use per person
- Less efficient irrigation
MEDCs (More Economically Developed)
- Higher industrial use
- Higher domestic use per person
- More efficient irrigation technology
- More water recycling
In short-answer questions about differences between countries, focus on clear reasons such as climate (irrigation need), crop type, seasonal demand, and the efficiency of irrigation systems.
IB-style question — share of water used by farming [1]
A bar chart shows projected national water demand in 2030: agriculture 1800 km³, domestic 400 km³, industry 600 km³, energy 200 km³ (total 3000 km³). Calculate the percentage of total demand used by agriculture. [1]
How to answer it, step by step
- {"label":"**Set up the percentage**","body":"**Part ÷ whole × 100**<br>• Part = agriculture = 1800 km³<br>• Whole = total = 3000 km³"}
- {"label":"**Work it out**","body":"**Substitute then solve**<br>• (1800 ÷ 3000) × 100<br>• = **60%**"}
Final answer
Always write the % sign — an answer of '60' with no unit loses the mark.
IB-style question — why farming water use changes over time [1]
A graph for a farming region shows water used for irrigation rising sharply each summer, then falling each winter. Give one reason why the water used for farming changes over time. [1]
How to answer it, step by step
- {"label":"**Link the change to a cause**","body":"**Don't just say 'it goes up'**<br>• Crops need more water in the growing season (summer)<br>• Low rainfall/high heat means more irrigation is needed"}
Final answer
Name the reason for the variation (e.g. dry summers) — a bare 'farmers use more water' is too vague.