IB ESS HL 4.2.4 Increasing Water Supplies Questions
Compare dams, transfers, desalination, recycling and other water-supply strategies.
- Syllabus
- First assessment 2026
- Course
- ESS HL
- Level
- HL
Exam points
- identify water-conservation and supply-enhancement strategies such as efficiency, rainwater harvesting, desalination and recycling
- explain how each strategy can increase available freshwater or reduce demand
- evaluate water strategies by comparing cost, reliability, environmental impacts, social access and long-term sustainability
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IB ESS HL 4.2.4 Increasing Water Supplies Questions question 1
[Maximum number: 7]
Evaluate rainwater harvesting and desalination as a means of sustainably managing water supply.
Rainwater harvesting (4 max):
Pros:
a. Low cost supply of water;
b. Low environmental impact/low technology;
c. Renewable supply / reduces use of potable water;
Cons:
d. Quantity very limited for agricultural purposes;
e. Weather/climate dependent;
f. May contain atmospheric pollutants / isn't generally potable;
Note to examiners: Award 3 max if only pros or only cons are addressed
Desalination (4 max):
Pros:
g. Vast supply of sea water available;
h. Produces potable water;
i. Independent of climate/precipitation;
j. Provides water security/independence;
Cons:
k. High cost supply:
I. Limited to coastal location;
m. Disposal of leftover salt;
n. Requires excessive energy supply;
o. Produces significant noise pollution;
Note to examiners: Award 3 max if only pros or only cons are addressed
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