Water sources and rising demand
Water supply is water collected from a source, treated and distributed for domestic, farming and industrial use. Sources: surface water (rivers/lakes, stored in a reservoir behind a dam); groundwater from an aquifer via boreholes; rainwater harvesting; desalination of seawater; water transfer schemes; and recycled wastewater. Demand rises everywhere from LINKED causes -- population growth, rising incomes, industry, irrigation (the largest global user) and urbanisation.
Physical vs economic water scarcity
Water shortage (scarcity/stress) is when demand exceeds the water reliably available. Two causes: PHYSICAL scarcity -- genuinely too little water (low rainfall, drought, dry climate); and ECONOMIC scarcity -- water exists but people can't access it for lack of infrastructure or investment. Management differs by cause: SUPPLY-SIDE raises the amount available (dam, transfer scheme, boreholes, desalination); DEMAND-SIDE cuts use (metering, conservation, leak repair, recycling).
Clean water, sanitation and disease
Potable water is safe to drink; sanitation is the safe disposal of human waste. Where both are lacking, water and food are contaminated, spreading water-borne diseases -- cholera, typhoid, dysentery -- mainly by the FAECAL-ORAL route: pathogens from untreated waste enter a water source that is then drunk. Consequences: high child mortality, lost schooling (often girls who collect water), lost income. Improvement combines treatment, sanitation and hygiene education.
Drawn from real examiner reports.
Water supply ≠ HEP/energy answer
A reservoir can supply BOTH water AND hydro-electric power, so weaker answers drift into HOW ELECTRICITY IS GENERATED, not water SUPPLY -- a different question (Energy, 3.5). A water-supply answer stays on how the scheme provides drinking/irrigation water: its SOURCE, storage and treatment. Avoid vague reservoir detail -- give located specifics (river, length, population).
Digest (## 3.6 Water): water-supply case studies are sometimes substituted with energy/HEP content, and reservoirs described vaguely ("it's big") instead of via located features (length, shape, scale). (s22 Paper 11 Q5(b)(i), Q6(c))
Name the supply METHOD, not just treatment
The strongest water-supply case studies NAME a specific supply method -- rainwater harvesting, groundwater via boreholes, a reservoir, a transfer pipeline, or desalination. Treatment (making it safe) and conservation answer DIFFERENT questions from the SOURCE of supply. Check the focus: is it supply, treatment, or conservation?
Digest (## 3.6 Water): the best water-supply case studies integrate a specific supply METHOD (rainfall harvesting, underground water) rather than focusing solely on treatment or domestic conservation, which is a different question. (s23 Paper 11 Q6(c))
"Clean water" is too vague
"Clean" is a vague term flagged as a credit-blocker. "Don't have clean water" is too vague alone. Specify the MECHANISM: water is unsafe because contaminated with waste carrying pathogens that cause diseases like cholera and typhoid; it is made potable by a named process -- filtration, chlorination, or boiling. "Pollution" likewise needs a type (sewage, run-off, effluent).
Digest (## Cross-cutting exam technique): vague/unqualified terminology -- including "clean/green" -- is the most repeated credit-blocker overall. (all four sittings, Paper 1 key messages)
Supply-side vs demand-side management
Keep the two management types distinct. SUPPLY-SIDE increases the AMOUNT available -- a new dam, transfer scheme, boreholes or desalination. DEMAND-SIDE reduces how much is USED -- metering, fixing leaks, efficient fittings, recycling. Answers often list only supply-side "build more" measures; a strong answer matches the strategy to the cause and combines both.
Match the fix to the scarcity type
The right management depends on WHICH scarcity you face. PHYSICAL scarcity (too little water) is tackled by increasing supply (new sources, transfer schemes, desalination). ECONOMIC scarcity (water exists but is unreachable) is tackled by INVESTMENT in infrastructure to reach water already there. A new dam for an economic-scarcity area answers the wrong problem.
Sanitation ≠ water supply
Sanitation and water supply are linked but different. Water SUPPLY provides water safe to drink; SANITATION is the safe disposal of human waste. Poor sanitation is what CONTAMINATES water via the faecal-oral route, so improving one without the other has limited effect. When a question asks about sanitation, write about waste disposal, not just drinking water.
Not all shortage is too little rain
Candidates often assume a shortage means too little rainfall -- physical scarcity. Much global shortage is instead ECONOMIC scarcity: water exists nearby but people can't access it for lack of infrastructure or money. Some very WET regions still lack reliable clean water for this reason. State WHICH scarcity applies: physical needs more supply; economic needs investment.
Clear-looking water can still be unsafe
Many pathogens are invisible, so water can look perfectly clear yet be heavily contaminated and unsafe. Visual clarity is not a test of potability -- water must be tested and/or treated (filtration, chlorination, or boiling) before it is genuinely safe. This is why "clean" is so vague: visually clear, or actually treated and pathogen-free? Not the same.
Digest (## Cross-cutting exam technique): vague/unqualified terminology -- "clean/green" -- recurs as the most repeated credit-blocker, supporting precision about what "clean" water means. (all four sittings, Paper 1 key messages)
Identify the question's exact focus
Water questions have three easily-confused foci: SUPPLY (obtaining it), TREATMENT (making it safe), and MANAGEMENT (reducing demand). Answering the wrong one wastes good geography. Pin down which is asked, then match the command word -- describe, explain, or suggest.
Level 3 on the 7-mark water case study
The water 7-marker rewards place detail plus developed reasoning, not a list. Top band: name a REAL scheme (e.g. Singapore's Four National Taps); give named methods (NEWater, desalination, imported water, local catchment); and link each to HOW it meets demand for that place.
Quote data and use comparative words
On data and compare questions, quote exact figures with units, not "about" or "most", and join a comparison with comparative words. Figures side by side are not a comparison. For a trend, state the direction, support it with values, and note any change in rate.
Full notes, flashcards, Q&A and the topic quiz for every premium subject.
Premium plans are US$8.99/month or US$49.99/year — first month free.
Studying with a parent's blessing? Show them this.
