The Hong Kong government should reconsider its water import deal with mainland China and reduce its reliance on it, according to a research report by a local think tank. Civic Exchange said the city should diversify and modernise its water sources by using more reclaimed water, or treated waste water, particularly for non-potable uses, such as irrigation and toilet flushing. Up to 80 per cent of Hong Kong’s water is imported from the Dongjiang in Guangdong, for which the Water Supplies Department (WSD) spends about HK$4.8 billion ($616 million) a year under the current agreement with the mainland. The deal is set to be renegotiated next year. “Water from the Dongjiang is indispensable for Hong Kong, but the city should look at other sources to ensure the sustainability of the river for both Hong Kong and other cities in the Pearl River Delta,” Civic Exchange senior adviser Natalie Chan said on Tuesday. Hong Kong has been importing water from the Dongjiang – or East River – since 1965. Under the “lump sum package” approach, adopted in 2006, the annual supply ceiling is set at 820 million cubic metres. The import amount is then adjusted on a monthly basis according to the needs of Hong Kong and rainfall in the city, to avoid excess supply. However, Hong Kong pays for the full 820 million cubic metres no matter how much water is actually used each year. The deal has been criticised for being too inflexible and critics have said the city should only pay for what it uses. Civic Exchange also suggested the WSD should lower the supply ceiling, but did not say how much it should be decreased to. Can Hong Kong strike a better deal on supply from mainland China? It suggested the government to set a more ambitious target for the use of reclaimed water, including harvested rainwater and treated waste water, to reduce its reliance on water from the Dongjiang. In its review of the Total Water Management Strategy in September this year, the WSD said it would expand the use of reclaimed water to 2.5 per cent of the total water supply from zero at present. But, Lee said the target should be expanded to a more ambitious 20 per cent. Civic Exchange associate researcher David von Eiff also said the government’s plan to use desalinated water as a source was unsustainable as the process was too energy-intensive, requiring six to eight times as much electricity to produce compared to current freshwater supplies. “The WSD is already the largest user of electricity in the government. So, if they are worried about their carbon footprint, they will have to be careful about how much desalinated water they want to use,” he said. A desalination plant in Tseung Kwan O is set to begin operation in 2023, and is expected to provide 5 per cent of the city’s potable water. He said more public education about the true cost of Hong Kong water could help the government in its push for a more sustainable water source. “If people were more aware of where our water comes from and how much it is bought for, there would be more of an appetite for modernising the water sources quickly,” von Eiff said. No room for lowering limit on Hong Kong water supply from mainland, expert says In an emailed response to the Post , the WSD said the “lump sum package” deal was adopted for more flexibility, but agreed the deal was ripe for review after being in force for more than 10 years. “We set up a working group with the Guangdong authorities in August 2017 to review the deal,” the WSD said, adding it was too early to disclose more details. The WSD said increasing the percentage of reclaimed water would require extensive upgrades of sewage treatment plants and the construction of water reclamation facilities and supply networks, which would require large resources and electricity, cause disturbance to the community, and emit more carbon. “[Civic Exchange’s] proposal needs to be carefully evaluated,” said the WSD. The department further said the desalination facility in Tseung Kwan O would use 3.5 kilowatts of electricity per hour to produce one cubic metre of fresh water, which was consistent with similar facilities globally.