Providing an adequate water supply for Hong Kong has always been difficult because there are few natural lakes, rivers or substantial groundwater sources and of its high population density. About 70% of water demand thus is met by importing water from the Dongjiang River in neighboring Guangdong province. In addition, freshwater demand is curtailed by the use of seawater for toilet flushing, using a separate distribution system.
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Water supply in Hong Kong initially came only from local sources, including numerous small dams built in the valleys of the territory.
Until 1964 water rationing was a constant reality for Hong Kong residents, occurring for more than 300 days per year. The worst crisis occurred in 1963-64 when water was delivered only every 4 days for 4 hours each time. The city-state then embarked on a three-pronged approach to supply water to a population that increased from 1.7 million in 1945 to about 6 million in 1992. The approach involved seawater flushing, the construction of larger freshwater reservoirs in bays that used to be covered by the sea, and water imports from mainland China.[1]
In 1955 seawater was first used to flush toilets in a pilot scheme, followed by installation in all new houses and in selected districts beginning in 1957.[2] In 1960 legislation was introduced to promote seawater flushing on a larger scale, followed by substantial investments in a separate network although the system was unpopular due to the need to build a separate plumbing network in each house. Seawater initially was sold, but from 1972 on it was provided for free and the costs of the system were recovered through the drinking water tariff. In 1991, about 65% of Hong Kong's households used seawater for flushing. By 1999, this percentage had increased to 79%.[3] However, despite this success in the introduction of this unique system, it remained a partial solution that had been unable to resolve the water crisis of the 1950s, 1960s and 1970s by itself.
In 1957 construction began on the first dam to close off a natural sea bay, the Shek Pik Reservoir, using it to store freshwater that had previously been lost to the sea during the rainy season. The reservoir was completed in 1963. It was followed by the construction of two other larger reservoirs of the same type. After the Plover Cove Reservoir was completed in 1968 and there was no more water rationing until 1977. With the completion of the High Island Reservoir in 1978, continuous supply was re-established. However, water rationing had to be reintroduced for the last time in 1980-81. Between 1965 and 1982 water had to be rationed 7 more times, often for many months with interruptions of up to 16 hours per day. In order to maintain the competitiveness of Hong Kong, rationing was only imposed on residential users while industry, the city's main water user, was exempted from rationing. However, rationing was finally overcome in 1982 thanks to water imports.[1]
In 1960 Hong Kong began importing water from outside its borders through the Dongjiang - Shenzhen (Dongshen) Water Supply Scheme. After many extensions and upgrades the system today consists of a pipeline from from Qiaotou Town of Dongguan to a reservoir in Shenzhen next to Hong Kong. Water imports from the Pearl River increased gradually from 23 million cubic meter/year under a 1960 agreement until a fifth agreement signed in 1989 which allowed for up to 1100 million cubic meter/year. Water imports thus played a crucial role in alleviating Hong Kong's water crisis, accounting for 70% of the territory's water supply in 1991. The People's Republic of China has never exercised the "water weapon" in its relationship with Hong Kong. China needed foreign exchange and between 1979 and 1991 alone Hong Kong paid China almost 4 billion Hong Kong Dollars (about US$ 500 million applying the 1991 exchange rate) for water imports.[1]
Desalination had been one source of water supply in Hong Kong. A large desalination plant was commissioned in Lok On Pai in 1975, but was decommissioned again in 1981 because its operation was more expensive than importing water from Dongjiang.[3]
The pollution of raw water supplied to Hong Kong became an increasing concern that triggered a variety of activities to protect the quality of raw water. In 1998 the intake of the water pipeline was moved further upstream on the Dongjiang River where water quality was better. In 2003 a 83km dedicated aqueduct was completed, thus reducing the vulnerability of the supply to pollution. Furthermore wastewater treatment plants were constructed in settlements in the Dongjiang basin and polluting industries were removed, thus protecting the water at the source.[4] In 2006 a Water Supply Agreement has been signed with Guangdong Province for "flexible" supply of Dongjiang water.[2] The agreement allows for less water to be withdrawn when reservoirs in Hong Kong are full, and more water to be withdrawn in times of drought, while the annual payment remains the same. Under the new agreement, Hong Kong pays fixed lump sums of HK$2,959 million, HK$3,146 million and HK$3,344 million for 2009, 2010 and 2011 respectively.[5]
In the 2003 the government of Hong Kong announced what it called a "total water management programme". In 2005 a study was commissioned whose results were broadly discussed. Based on the study the government reaffirmed its approach to water management, but also started new initiatives concerning leakage reduction, water conservation, greywater reuse, rainwater harvesting, as well as pilots for the reuse of reclaimed water and desalination. For example, it plans to provide reclaimed water from Shek Wu Hui Sewage Treatment Works for consumers in Sheung Shui and Fanling for toilet flushing and other non-potable uses, as well as pilot desalination plants in Tuen Mun and Ap Lei Chau.[6]
Hong Kong's three main sources of water are supply from Guangdong Province; internal freshwater sources stored in reservoirs; and seawater used for flushing toilets. Dongjiang is Hong Kong's major source of water. The designed maximum capacity of the supply system is 1.1 billion cubic metres per annum. The supply contract, costing HK$2 billion a year, has helped the city's economy grow without the interruption of water shortage, although the payment constitutes only 0.15 per cent of Hong Kong's HK$1.3 trillion gross domestic product. About one-third of Hong Kong's 1,098 square kilometres has been developed as water catchments including both reservoirs behind dams on land and three 'reservoirs in the sea', the Shek Pik Reservoir, the Plover Cove Reservoir and the High Island Reservoir.
An interesting facet of the waterworks is the seawater supply systems with their separate networks of distribution mains, treatment facilities for screening and disinfection, pumping stations and service reservoirs. 80% of the population, including nearly all housing estates in Hong Kong Island and other densely populated districts, receive sea water for flushing. Some remote districts in the New Territories and some outlying islands do not use the system.[1] In 2010, an average of about 740 000 cubic metres of seawater was supplied each day,[7] up from 330 000 cubic meters each day in 1990/91. Seawater is used to flush toilets and accounts for about 22% of total water use in 2008-09.
More than 70% of Hong Kong's water is used by industry and services, particularly the textile, metal-working and electronics sectors in manufacturing, and hotels and restaurants in services.[1]
All figures are in million cubic metres
| Fresh Water | 2003 - 2004 | 2004 - 2005 | 2005 - 2006 | 2006 - 2007 | 2007 - 2008 | 2008 - 2009 |
| Annual | 963.99 | 954.62 | 966.92 | 963.59 | 950 | 957.31 |
| Daily Average | 2.63 | 2.62 | 2.65 | 2.64 | 2.60 | 2.62 |
| Highest Daily | 2.91 | 2.79 | 2.82 | 2.84 | 2.81 | 2.86 |
| Seawater | 2003 - 2004 | 2004 - 2005 | 2005 - 2006 | 2006 - 2007 | 2007 - 2008 | 2008 - 2009 |
| Annual | 244.31 | 259.83 | 261.63 | 261.66 | 274.23 | 271.08 |
| Daily Average | 0.67 | 0.71 | 0.72 | 0.72 | 0.75 | 0.74 |
Hong Kong's water infrastructure consists of the following water treatment plants, pumping stations and reservoirs.
The supply is fully treated by chemical coagulation, sedimentation (at most treatment works), filtration, pH value correction, chlorination and fluoridation. The water is soft in character and conforms in all respects — both chemically and bacteriologically — to standards for drinking water set by the World Health Organization. However residents often prefer to boil the water before drinking, although this is generally not necessary.[8]
The main water treatment plants are:
The total storage capacity of Hong Kong's reservoirs is 586 million cubic metres. The reservoirs and their storage are tabulated below:
| Reservoir (Year on reservoir) | Reservoir supply storage m³ |
| Pok Fu Lam 1877 | 231,000 |
| Tai Tam 1889 | 1,490,000 |
| Tai Tam Byewash 1904 | 80,000 |
| Tai Tam Intermediate 1907 | 686,000 |
| Kowloon 1910 | 1,578,000 |
| Tai Tam Tuk 1917 | 6,047,000 |
| Shek Lei Pui 1925 | 374,000 |
| Kowloon Reception 1926 | 121,000 |
| Aberdeen (2 Res.) 1931 | 1,259,000 |
| Kowloon Byewash 1931 | 800,000 |
| Shing Mun (Jubilee) 1936 | 13,279,000 |
| Tai Lam Chung 1957 | 20,490,000 |
| Shek Pik 1963 | 24,461,000 |
| Lower Shing Mun 1965 | 4,299,000 |
| Plover Cove 1968 | 229,729,000 |
| High Island 1978 | 281,124,000 |
The Water Supplies Department is responsible to collect, store, purify and distribute potable water to consumers, and provide adequate new resources and installations to maintain a satisfactory standard of water supply. The department also supplies seawater for flushing toilets.
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