With the search for new water sources reaching its limits, Singapore is setting its sights on another key area of research to make sure it squeezes more value from each drop of clean water it produces.
A major chunk of the $453 million that has gone into water research and development here has gone into making water treatment processes less of a drain on electricity.
"We are pushing the frontier of water technology to tackle the pressing challenges in energy and sludge management efficiency," Mr Harry Seah, assistant chief executive for future systems and technology at national water agency PUB, said on Wednesday.
This comes as Singapore becomes increasingly reliant on its two weather-proof sources of water - desalination and water re-use - against a backdrop of erratic weather, he said.
"The challenge is to ensure that technological advancements continue to keep up with increasing water demand so these sources remain sustainable," he added.
Mr Seah was giving the media an update on Singapore's research into water ahead of a global water conference, the Singapore International Water Week, at Marina Bay Sands next week.
Up until the early 2000s, Singapore was reliant on its reservoirs or Malaysia's Johor River to meet its water needs.
A new "tap" came online in 2002 with the launch of reclaimed used water, or Newater, and again in 2005 when the first desalination plant in Tuas was completed.
Today, both these taps can meet up to 70 per cent of Singapore's demand of 430 million gallons a day - equivalent to 774 Olympic-size pools. The two taps are projected to help meet up to 85 per cent of future water demand in 2060. Demand for water is expected to double by then.
But both these water treatment methods require plenty of energy.
Between five and 17 times more electricity than that used to treat rain water is needed to produce water through desalination or treatment of used water. The latter also produces sludge, which is ultimately landfilled.
PUB said that meeting future demand with today's technology will see its electricity requirement go up four times to 4,000 gigawatt hours (GWh) a year, with the sludge generated doubling to 600,000 tonnes a year by 2060.
This is unsustainable and can be overcome only by leveraging technology, said PUB, adding that Singapore's long-term goal is to meet water demand in 2060 without going beyond the current amount of energy used and sludge produced.
While Singapore is not constrained by energy as it is by water and land, it is still in its interests to keep this requirement low to save on costs, and fulfil its international climate pledge to reduce its carbon footprint, Mr Seah said.
Assistant Professor Winston Chow from National University of Singapore's geography department said that while new "taps", such as groundwater extraction, can be explored further, Singapore has succeeded in boosting its water supply through desalination and Newater.
"It's thus more sensible to invest in making these taps more efficient and cheaper for both domestic and commercial water users here."
Water expert Asit Biswas, distinguished visiting professor at the Lee Kuan Yew School of Public Policy and Stockholm Water Prize winner, warned that managing demand has to be an essential part of ensuring Singapore's future water security.
"We have reached a plateau in what technology can do for us in increasing water supply. Further advances are likely to be incremental rather than transformational," said Prof Biswas.