ORANGE COUNTY, California - Singapore has ramped up efforts to study whether and how the country's underground water can be extracted for use.
National water agency PUB has formed a team of international experts to advise it, and will dig its first exploratory monitoring wells in the next few months.
It is interested in the subterranean Jurong rock formation in western Singapore, which could hold water-bearing layers of rock called aquifers.
Even if Singapore is unable to extract substantial water from them regularly, such aquifers could act as "water banks" for drought periods, said PUB chief technology officer Harry Seah.
While there is no timeline for when this water could contribute to Singapore's supply, the exploratory efforts will help to prepare the country, he said.
"We are building up our expertise in the field... and if groundwater does become feasible, we will have a ready team to manage the groundwater resource."
The PUB plans to install 20 to 30 monitoring wells in western Singapore and monitor the flow of water through them for six to 12 months. These wells will be about 5cm wide and 10m to 20m deep. Their locations are being worked out, but likely options include green verges alongside roads and other public areas.
Among other things, they will help find out where rainwater goes after it seeps into the ground.
"For example, we want to know how much of it goes vertically down into aquifers, and how much horizontal movement there is instead," said Mr Seah.
This information will be useful when Singapore looks into how much water is available, how much of it can be safely extracted, and how fast it can be extracted such that rainfall can naturally replace the removed water.
To speed up the learning process, PUB has asked six experts around the world for help. They include: Lord Ronald Oxburgh, a noted geologist and geophysicist; Professor Ken Howard, president of the International Association of Hydrogeologists and an expert in urban groundwater management; and Mr Roy Herndon, chief hydrogeologist at the Orange County Water District in California, which has been extracting groundwater for decades.
Although he played down suggestions by reporters that underground water could be Singapore's fifth tap - after imports from Malaysia, recycled used water and treated seawater and rainwater - Mr Seah added that there is always urgency for the PUB to explore new ideas.
The PUB studied underground water in eastern Singapore in the 1990s, but the data from the technology used then did not give the agency "adequate confidence" that extracting the water would be sustainable or safe.
"As Singapore progresses, the water demand will keep growing. If we continue with business as usual, the energy needed will grow much faster as we ramp up desalination and Newater to meet demand. It's not sustainable," said Mr Seah.
While the PUB has embarked on research to reduce the energy needed for water treatment, "groundwater is freshwater", he added. "If we have abundant rainwater, we can inject some into the ground, increase our storage... extract the water to meet our demand and give us more buffer for drought."
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