Managing and saving water
FoundationWater management means new supply (desalination such as the Tseung Kwan O plant, and Dongjiang imports) plus saving (pricing, leak repair, daily habits). About 70 to 80 percent of Hong Kong's fresh water comes from the Dongjiang — saving water is everyone's job.
- Water management needs both: new supply (desalination, Dongjiang, reclaimed water) and saving (pricing, leaks, habits)
- About 70 to 80 percent of Hong Kong's water is Dongjiang water; the 1963 rationing led to the 1965 agreement
- Tseung Kwan O's first stage adds about 5% — a second source; desalination needs green power
文體小知識：方案評估課：開源（化淡、東江水）與節流（定價、節水習慣）並重，答題時兩邊都要舉香港實例。
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1Water strategy has two directions: new supply and saving. New supply means reservoirs, transfers, reclaimed water and desalination; saving means fixing leaks, fair pricing, efficient fittings and changed habits. Both are needed — new sources are costly and slow, while savings show results at once.
2Desalination is the flagship of new supply: reverse-osmosis membranes filter salt from seawater, rain or no rain. In the Middle East, Israel draws about 80% of household water from desalination and reuse; Hong Kong's Tseung Kwan O plant supplies about 5% of the city's water in its first stage, with room to reach about 10% — a second source beside the Dongjiang. Yet desalination is power-hungry and costly per cubic metre, and needs renewable energy to keep its carbon footprint down.
3Hong Kong's supply history is a textbook of new supply: in the great drought of 1963 water was restricted to four hours every four days, pushing the government to buy Dongjiang water from Guangdong. Imports began in 1965; today the annual cap is about 820 million cubic metres, some 70 to 80 percent of Hong Kong's fresh water. The Dongjiang stabilised Hong Kong's growth — but created reliance: Guangdong's own cities are booming, competition in the basin is rising, and dry years tighten allocations.
4On saving, the Water Supplies Department runs the 'Let's Save Water' campaign, water-efficiency labels and smart-meter trials; personally, showering instead of bathing, taps off while brushing teeth, and reusing rinsing water on plants each save tens of litres a day. Singapore goes further: reclaimed NEWater meets about 40% of demand, and with desalination, local catchment and imports it runs on 'Four National Taps'. The future of water lies not in finding new sources but in using every drop well.
1Summary 重點摘要
Water management means new supply (desalination such as the Tseung Kwan O plant, and Dongjiang imports) plus saving (pricing, leak repair, daily habits). About 70 to 80 percent of Hong Kong's fresh water comes from the Dongjiang — saving water is everyone's job.
2Vocabulary cards Vocabulary
Removing salt from seawater (e.g. reverse osmosis); weather-proof but power-hungry and costly.
Pressing seawater through a membrane to leave salt behind — the method used at the Tseung Kwan O plant.
Fresh water piped to Hong Kong from Guangdong's Dongjiang since 1965 — now about 70 to 80 percent of supply.
Limiting when or how much water people may use; in the 1963 drought Hong Kong had four hours every four days.
Charging for water to reflect cost and scarcity and encourage saving; Hong Kong uses a tiered tariff.
Labels grading showers, taps and other fittings by water efficiency so buyers can choose savers.
Treated wastewater fit for reuse (irrigation, flushing); Singapore's NEWater is the famous example.
Singapore's supply strategy: local catchment, imported water, NEWater and desalination together.
Meters that log use in real time and detect leaks, helping users and utilities manage demand.
3Step by step Steps
- Para 1: new supply and saving, two legsWater management runs on two legs. Developing new supply means reservoirs, inter-regional transfers, reclaimed water and desalination; curbing demand means leak repair, pricing to shape use, efficient fittings and saving habits. Fixing heavy leaks in one trunk main can save enough for a whole small town — proof that saving is often more cost-effective than new supply and should come first.
- Para 2: desalination, promise and priceDesalination turns seawater fresh through reverse osmosis, giving coastal cities a source immune to weather. Israel draws about 80% of its household water from desalination and reuse, letting a desert nation live without want; Hong Kong's Tseung Kwan O plant, in its first stage, will supply about 5% of the city's use. The price is heavy power use per cubic metre, far costlier than conventional sources — and if fossil plants provide the electricity, climate targets suffer, so green power must accompany it.
- Para 3: the Dongjiang, history and trade-offsThe Dongjiang is the backbone of Hong Kong's supply. In the great drought of 1963, water came only four hours every four days; the Dongjiang scheme, completed in 1965, transformed the situation. Today the annual cap is about 820 million cubic metres, meeting 70 to 80% of use. The strength is reliability even in drought years; the costs are rising prices, risk concentrated in a single source, and allocation competition with the growing cities of Guangdong along the river.
- Para 4: saving water at home in Hong KongSmall habits add up to astonishing totals: a five-minute shower uses about 100 litres against 200-plus for a bath, so switching alone saves over half each time; turning off the tap while brushing teeth saves about 6 litres. The Water Supplies Department's 'Let's Save Water' website offers a personal water calculator and tips. If seven million people each save a few litres a day, the yearly total runs into millions of cubic metres.
- Para 4: Singapore's Four National TapsSingapore is famous for its Four National Taps: local catchments covering about two-thirds of the island collect rain; NEWater turns highly treated used water into fresh supply, meeting about 40% of demand; desalination and imports from Malaysia top up the rest. A tiny state with almost no natural endowment achieved water security through diverse sources and a national saving culture — proof that policy and technology can overcome geography, a lesson for Hong Kong.
- Answer framework: new supply plus saving plus evaluationFrame water-management answers in three moves: three new-supply examples, such as desalination, the Dongjiang import and reclaimed water; three saving examples, such as pricing, leak repair and changed habits; then an evaluation comparing cost, environmental impact and reliability. Desalination is reliable but power-hungry; saving is cheap but needs everyone. Conclude for a portfolio of measures, since no single method can secure water on its own.
4Diagrams Diagrams
5Worked example Example
Example: should Hong Kong keep relying on the Dongjiang or expand desalination? Assess both options.
- Dongjiang strengths: stable supply guaranteed even in drought, backing Hong Kong's growth for decades; the 1963 rationing shows local reservoirs alone cannot cope
- Dongjiang weaknesses: rising costs; 70 to 80 percent of supply from one source concentrates risk; Guangdong's growing cities sharpen competition for allocations
- Desalination strengths: immune to drought and under local control; Tseung Kwan O can grow to about 10% and cut reliance
- Desalination weaknesses: power-hungry and far costlier than Dongjiang water; large-scale plants raise emissions unless renewables supply them
- Answer: It is not either-or: the Dongjiang remains the backbone while desalination is the second source; with saving and reclaimed water, a diversified portfolio is Hong Kong's long-term water security. Tip: score each option on cost, reliability, environment and risk, and conclude with a 'portfolio', not a single pick.
6Common mistakes Mistakes
7Quick check Quick check
Q1What share of Hong Kong's water comes from the Dongjiang?
Q2What share of demand does the Tseung Kwan O desalination plant meet in its first stage?
Q3How was water rationed in Hong Kong's 1963 drought?
Q4What are Singapore's Four National Taps?
Q5List three personal water-saving habits.
8Recap Recap
- Water management needs both: new supply (desalination, Dongjiang, reclaimed water) and saving (pricing, leaks, habits)
- About 70 to 80 percent of Hong Kong's water is Dongjiang water; the 1963 rationing led to the 1965 agreement
- Tseung Kwan O's first stage adds about 5% — a second source; desalination needs green power
- Singapore's Four National Taps: catchment, imports, NEWater (about 40%), desalination
- Personal saving — showers over baths, taps off, reuse — adds up across millions of users