Water supply and sanitation in Hong Kong

Though multiple measures were made throughout its history, providing an adequate water supply for Hong Kong has met with numerous challenges because the region has few natural lakes and rivers, inadequate groundwater sources (inaccessible in most cases due to the hard granite bedrock found in most areas in the territory), a high population density, and extreme seasonable variations in rainfall.

[1] In addition, freshwater demand is curtailed by the use of seawater for toilet flushing, using a separate distribution system.

The territory, which was under the British colonial administration, then embarked on a three-pronged approach to supply water to an increasing population.

The strategy involved flushing toilets with seawater, the construction of larger freshwater reservoirs in bays that used to be covered by the sea, and water imports from mainland China.

[4] In 1960 legislation was introduced to promote seawater flushing on a larger scale, followed by substantial investments in a separate network.

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.

[5] In 1957 construction began on the first dam that would close off a natural sea bay and create the Shek Pik Reservoir.

After many extensions and upgrades, the current system consists of a pipeline from Qiaotou Town of Dongguan to a reservoir in Shenzhen next to 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.

Additionally, wastewater treatment plants were constructed in settlements in the Dongjiang basin and polluting industries were removed, thus protecting the water at the source.

For example, the government 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.

An interesting facet of the waterworks is the seawater supply system with its separate networks of distribution mains, treatment facilities for screening and disinfection, pumping stations, and service reservoirs.

The supply is fully treated by chemical coagulation, sedimentation (at most treatment works), filtration, pH value correction, chlorination and fluoridation.

[13] The main water treatment plants are: The total storage capacity of Hong Kong's reservoirs is 586 million cubic meters.

[15] One of the largest facilities is the Sha Tin Sewage Treatment Works covering an area of 28 hectares.