With no natural lakes, large rivers or underground water, Hong Kong, a densely populated centre of trade and industry, faces the daunting task of securing a stable and adequate supply of water to meet its development needs. The undulating nature of much of the territory's 1,104 km2 of land has made collection and storage of the precious rainwater a big challenge.
Currently, Hong Kong has a 3-pronged water supply system, comprising rainwater from local catchments, imported water from Dongjiang in Guangdong and seawater for toilet flushing.
In 2019, the total water consumption was 1.303 billion cubic metres. Over the years Hong Kong has developed an extensive surface water collection and storage system. About one third of Hong Kong's land is used as water gathering grounds where surface runoff is collected for storage. Most of these areas are also designated as part of the territory's Country Parks, helping conserve the precious natural environment of Hong Kong. Despite all these efforts, in 2019, the water collected from the local water gathering grounds (local yield) was 273 million cubic metres, meeting about 21% of our water demand.
The local yield is inadequate to meet the fresh water demand in Hong Kong. It also fluctuates significantly and is unreliable, the difference in the quantities of local yield could be up to 200 million cubic metres. Confronted with the challenge of inadequate and unreliable local yield, Hong Kong has been importing Dongjiang (DJ) water since 1965 to meet local water demand. In 2019, about 55% of our water supply is imported from Dongjiang (East River) in the Guangdong Province over a long distance of more than 70 km.
Nowadays, many places in the world are still using fresh water for toilet flushing. On the other hand, the WSD has been supplying seawater for flushing in government and government-aided high density development schemes since the late 1950's. Up till now, Hong Kong is one of the few places extensively applying seawater for flushing. The use of such a sustainable resource continues to play an important role in Hong Kong's water management. In 2019, total 313 million cubic metres of seawater is supplied, conserving an equivalent amount of fresh water.