Water supply in Hong Kong

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. Although the annual rainfall averages 2 214.3 millimetres, this is insufficient to meet current demands — the average daily consumption of potable water during 2002/03 being 2.63 million cubic metres. About 70% of water demand thus is met by importing water from the Dongjiang River. In addition, freshwater demand is curtailed by the use of seawater for toilet flushing, using a separate distribution system.

ources of water

Hong Kong's two main sources of water are rainfall from natural catchments; supply from Guangdong Province; and seawater used for flushing toilets. Desalination had been one source of water supply in Hong Kong. A plant was set up in Lok On Pai. The plant later ceased its operation for its expensive cost compared to importing water from Dongjiang. The plant was finally dismantled.

Rainfall and storage of runoff

About one-third of Hong Kong's 1 098 square kilometres has been developed as water catchments. Hong Kong is dependent on adequate storage for the maintenance of a regular supply. Shortage of natural storage reservoir sites led to the construction of Hong Kong's first 'reservoir in the sea' at Plover Cove - the Plover Cove Reservoir. The initial scheme, completed in 1967, was created by damming, and draining an inlet of Tolo Harbour and had a storage of 170 million cubic metres. The storage was increased in 1973 to 230 million cubic metres by raising the dam. A similar but larger scheme at High Island, completed in 1978, created the High Island Reservoir that has a capacity of 281 million cubic metres.

upply from Guangdong

Dongjiang is Hong Kong's major source of water, and will meet all future increase in demand. In 1960, the agreement was reached with the Guangdong authorities whereby Hong Kong would purchase 23 million cubic metres of water each year. The supply from Guangdong stipulated under the latest agreement was increased to 810 million cubic metres a year in 2003. This will continue to increase in 10 million cubic metres per annum up to 2004, beyond which the annual supply quantity will be subject to further review. 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.

eawater for flushing

An interesting facet of the waterworks is the seawater supply systems with their separate networks of distribution mains, pumping stations and service reservoirs. In 2002/03, an average of about 650 000 cubic metres of seawater was supplied each day, up from 330 000 cubic meters each day in 1990/91. Seawater is used to flush toilets and accounts for about 15% of total water use. Nearly all housing estates in Hong Kong Island and other densely populated districts receive sea water for flushing. Only some remote districts in the New Territories and some outlying islands do not use the system. [ Chau 1993, p. 68-69 and p. 72 ]

Consumption

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. [ Chau 1993, p. 68 ]

All figures are in million cubic metres

Water Infrastructure

Hong Kong's water infrastructure consists of the following water treatment plants, pumping stations and reservoirs.

Water treatment

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, the local people prefer boiling the water before drink.

The main water treatment plants are:

*Sha Tin
*Pak Kong
*Au Tau
*Tsuen Wan
*Tuen Mun
*Tai Po
*Yau Kom Tau
*Ma On Shan
*Ngau Tam Mei

Pumping Stations

* Muk Wu No.2 & No. 3
* Tai Po Tau, Tai Po Tau No.2, No.3 & No.4
* Tai Mei Tuk & Tai Mei Tuk No.2
* Harbour Island

Reservoirs

The total storage capacity of Hong Kong’s reservoirs is 586 million cubic metres. The reservoirs and their storage are tabulated below:

Responsibility for water supply

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.

History

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. In the late 1950s seawater flushing had been introduced. However, the situation was only significantly improved through water imports and a massive program to dam off natural sea bays and using them to store freshwater.

In 1960 Hong Kong began importing water from outside its borders. 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. [ Chau 1993, p. 72 ]

Despite the efforts made to increase water supplies it was difficult to keep up with the increasing water demand from a population that increased from 1.7 million in 1945 to about 6 million in 1992. 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. [ Chau 1993, p. 68-69 ] After 1982 no more rationing was necessary.

Sources

*Chau, K.W.: Management of Limited Water Resources in Hong Kong, Water Resources Development, VOl. 9, No. 1, 1993

References

ee also

* Hydrology
* Plumbing
* Reservoirs of Hong Kong
* Water
* Water pipes
* Water resources
* Water supply
* Water supply and sanitation in China
* Water quality