Hong Kong lacks natural lakes, rivers and abundant groundwater, and the water supply problem has never been easy to solve.
According to data from the Hong Kong Water Service Department, in 2021/22, the average daily water consumption in Hong Kong reached 2.89 million cubic meters, while the average rainfall in the same year was only 2431.2 mm, which was completely insufficient to cope with the huge demand.
Of course, the Dongjiang water transported from Guangdong Province to Hong Kong since 1965 has helped a lot and has now become the main water source in Hong Kong. In 2021/22, Guangdong imported 784 million cubic meters of Dongjiang water, accounting for about 70 to 80% of Hong Kong's water consumption.
For Hong Kong, there is another unusual water project, which has helped greatly relieve local water demand. This project has created a "world's best" seawater supply system for Hong Kong.
In mainland cities, our household water is used to extract rivers or groundwater, and enter the house through reservoirs and tap water systems. That is to say, washing, cooking, drinking water, and flushing the toilet are all a set of pipes and a water source.
But in Hong Kong, real estate developers will install two sets of waterway systems, ready-to-eat water supply system and seawater supply system during the construction of buildings.
Hong Kong Water Services Department picture
Moreover, this seawater toilet flushing system is the world's first. In the 1950s, when water was quite difficult to use, Hong Kong developed this system in 1958 in order to save water. At present, the coverage rate of seawater has increased to 85% of the population, and Hong Kong has become one of the few cities in the world that use seawater to flush toilets on a large scale.
sustainable and free
Seawater is a sustainable source of water. According to data from the Water Service Department, in 2021/22, the average daily water supply of seawater in Hong Kong reached about 876,000 cubic meters, which means that flushing the toilet with seawater can save Hong Kong about 320 million cubic meters of food water throughout the year, equivalent to 20% of the total water consumption in Hong Kong.
In addition, there is another point that is particularly important to citizens, which is to use sea water to flush the toilet, which is completely free (even sewage discharge fee does not have to be paid), which to a certain extent reduces the people's water bill burden and also improves the cleanliness and hygiene of Hong Kong citizens. Of course, the Hong Kong government also stipulates that it is illegal to use seawater for other purposes.
In 2001, this seawater toilet flushing system in Hong Kong was awarded the "Chris Binnie Continuous Water Management Award" by the British Society of Water and Environmental Management, and Hong Kong has also become the first region outside Europe to win this honor.
system construction is not easy
In addition to being the world's first, why is Hong Kong's seawater toilet flushing system still known as the "world's best" until now? This is because running such a huge system is not easy, and Hong Kong is one of the few cities in the world that have overcome difficulties and insist on using sustainable resources such as seawater.
Hong Kong Water Services Department picture
For example, Macau, a neighbor of Hong Kong, actually considered using sea water to flush the toilet, but it was not possible in the end.
According to the Macau Government News Bureau, the reason is that the seawater quality in Macau is unstable, mixed with yellow mud and sand, so pre-treatment facilities are needed; and the underground pipeline space is crowded, making it difficult to lay a seawater pipeline network. In addition, each household in the indoor area must have an independent seawater system, which must be approved by all users in advance before implementation. The local government considers costs and technology and believes that there are difficulties in implementing seawater toilet flushing.
It is not difficult to see from Macau's statement that first, using seawater flushing toilets is the first problem of seawater quality. Although seawater treatment specifically used for flushing toilets does not need to meet the drinking water standards, the Hong Kong Water Services Department has also formulated the "Salty Water Water Quality Index for flushing toilets". The Water Services Department must first use a partition net to remove large impurities in the seawater, then disinfect it with hypochlorite , and confirm that the water quality meets the specified color, turbidity, odor and other requirements before it can be transported to the distribution reservoir for users to use.
Salt water quality indicators for toilet flushing
In addition, using the seawater supply system, a large number of special pipelines need to be laid. In Hong Kong, if a developer wants to access the seawater supply system, he must first be approved by the Hong Kong Water Supply Department and use materials that are resistant to saltwater erosion as water pipe material . Moreover, the Water Supplies Department will also need to equip this system with independent water distribution main pipes, pumping stations and water distribution reservoirs.
faces aging risks
However, this seawater supply system, which has gone through a lot of hardships, has also become a more serious issue in the aging of infrastructure in Hong Kong over time.
Recent news about salt water pipe burst
Now search for the word "salt water" in Hong Kong's search engines. The most common content is nothing more than "salt water pipe burst" and the impact of salt water pipe burst on citizens' lives.
Although the Water Services Department has started the "replacement and repair water pipes" in stages since 2000, and has completed the replacement task of 3,000 kilometers of water pipes in 2015.
water pipe burst cases also dropped sharply from about 2,500 a year at the peak of 2000 to 88 in 2017.
However, water pipe bursts in various districts still frequently make headlines, and the number of cases about 100 cases a year is still not small; and a salt water pipe breaks, which will affect residents of a community for hours without water, which is a big impact.
At present, according to local media reports, half of Hong Kong's water pipes are still facing aging problems, and replacing water hose is an urgent task, which shows that the Hong Kong government must continue to move towards a "proactive government" clearly and clearly, and solve the deep-seated problems of Hong Kong, which still requires long-term efforts.
(text/Reporter Shen Yuqing of this magazine)
This article is a new media article of Hong Kong's " Economic Guide ".
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