Hong Kong is one of the world’s most densely populated places and a central business hub in Asia. The former British colony is surrounded by sea in almost every direction and summers bring subtropical humidity and heavy rainfall. Despite what seems like an abundant supply of water, it suffers from water scarcity, and local think tanks predict that the effects of the climate crisis and industrial pollution will further threaten freshwater access.
“Reliable water supply may decrease under the plausible extreme climate change effects”, says a spokesperson of the Water Department in a written statement.
The few rivers and lakes spread across the islands’ landscapes do not catch enough rainwater to provide fresh water for Hong Kong’s more than seven million residents. Instead, Hong Kong imports at least two-thirds of its freshwater from China. But the climate emergency threatens the main supply of Hong Kong’s freshwater, and desalination will be only part of the solution.
An illusion of plenty
Every day more than 1.8 million cubic metres of water is extracted from the Dongjiang River in southern China and pumped across the border, crisscrossing Hong Kong in a system of public pipes which, if stacked on top of each other, would reach from Hong Kong to Alaska. It provides freshwater from the tap to some of the most remote of Hong Kong’s more than 60 islands. The system has worked without fail since 1982 when Hong Kong last had to ration its water.
It has provided a convenient solution for a place that is naturally water-scarce, allowing Hong Kongers to use more water on average than people in similarly wealthy places in the region, like Singapore. The trend is fuelled by relatively affordable water tariffs which are heavily subsidized and do not reflect the actual cost of freshwater in Hong Kong.
Because importing water is so lucrative, alternative sources of water were long considered not economically viable. In 1981, a fully functioning desalination plant was shut down after only four years of operation because the costs were deemed too high. This only changed when the Guangdong government started to cap the amount of water that can be extracted from the Dongjiang and raised prices.
The river provides water for 40 million people in eight major cities including Hong Kong. An economic boom in the Guangdong region, also known as China's economic powerhouse, has heightened competition for freshwater from the Dongjiang, bringing the river close to its extraction limits.
Extreme weather drives prices up
Even before the Dongjiang runs out of water, the costs of importing it will make the system unsustainable, says David von Eiff, an economist at City University in Hong Kong. In 2008, a two-year drought led the Guangdong government to increase prices. Following the drought, the price at which Hong Kong buys the water more than doubled from $2.3 per m3 in 2009 to $5.9 per m3 in 2019.
So far, Hong Kong residents do not feel the immediate impact, because prices for consumers remain extremely low. But rising temperatures, pollution, and extreme weather threaten the main pillar of Hong Kong’s water supply. Local think tanks predict that Hong Kong cannot continue to rely on the Dongjiang River for the majority of its freshwater supply. The Water Department admits that the effects of climate change on Hong Kong’s water supply are unpredictable and threatening.
Desalination as part of the solution
In a city surrounded by the ocean in almost every direction, desalination seems an obvious choice as an alternative source of water. The Hong Kong Water Department started building a new desalination plant in late 2019 that is expected to open in the second half of 2023. It uses reverse osmosis to turn ocean water into potable water. During the process, saltwater is forced through a semi-permeable membrane under high pressure, which allows freshwater to pass while retaining salts and other impurities.
Desalination is an energy-intensive process and creates a toxic side product that has twice the salt concentration as ocean water, according to a United Nations report. The Hong Kong Water Department has taken some measures to mitigate the high energy consumption of the desalination plant by installing photovoltaic panels, which are expected to provide for one-sixth of the electricity demand of the plant.
The biggest advantage of desalination is that it is not susceptible to the effects of the climate crisis. More than 170 countries use desalination plants, according to a United Nations study, with several small countries meeting 100% of their water demand through desalination. Saudi Arabia, which has a population four times the size of Hong Kong, gets half of its drinking water from desalination.
Saving valuable resources
The desalination plant in Hong Kong will provide between 5% and 10% of Hong Kong’s freshwater, a diminishingly small amount compared to what is needed. Although land has been reserved for a future expansion, the authors of a 2017 research report by local think tanks warn that the desalination plant is “at risk of being an expensive project with little overall impact on Hong Kong’s long-term water security”. They point to the great amount of freshwater that is lost on its way between source and tap and urge the water department to further invest in the repair and maintenance of pipes.
Approximately 15% of freshwater is currently lost due to leakages in water pipes. The Water Department argues that this is partly because of the hilly terrain of Hong Kong, which leads to unusually high pressure and causes frequent pipe bursts. But government reports show that by maintaining pipes properly, the amount of water wasted can be reduced significantly.
Twenty years ago, Hong Kong saw an average of six burst public water pipes every day. After replacing and rehabilitating more than 3000km of water pipes, it is now down to less than one burst water pipe per week. The authors of a 2019 research report by Civic Exchange, a local think tank, estimate that if the water department further reduced water lost from leakages to 8% by 2030, it could save enough freshwater to provide for more than half a million residents a year.
In the long term, Hong Kong will have to start using less freshwater. Sam Inglis, a former environmental research analyst at ADMCF, a local think tank, advocates for a stratified water allocation system, where everyone has equal access to enough water to live a dignified life, but overconsumption is disincentivized.
“Hong Kong is simply living beyond what is reasonable.”