Daily water usage has gone up by 5 per cent above average during the current dry spell.
Singapore will have to "re-evaluate the adequacy of our current plans" if the trend continues, Minister for the Environment and Water Resources Vivian Balakrishnan said.
He was responding in Parliament on Friday to MP David Ong (Jurong GRC), who asked at what point the country may have to consider water rationing, last seen in the 1960s.
Dr Balakrishnan reiterated that he does not see a need for water rationing in "the foreseeable future", as long as Singaporeans do their part to conserve water and cut usage.
Even so, he is "taking seriously" a suggestion from members of the public to conduct water- rationing exercises. These would remind people of the value of water, he said, and allow them to rehearse what may need to be done.
The two desalination and four Newater plants here have been running at near-full capacity during the dry spell, providing 55 per cent of the country's water needs.
Dr Balakrishnan stressed that despite the investments in desalination and Newater, imported water from Malaysia "remains an essential part" of Singapore's water supply.
He noted that the $300 million-plus thatSingapore spent to build the Linggiu dam across the Johor River had enabled both countries to draw more water, even during this dry spell.
"All these additional investments have been a premium that we have paid for greater security and diversity of our water supply," he said.
Singapore aims to achieve water self-sufficiency by 2061, the year the second water agreement with Malaysia expires, he added, reiterating Foreign Minister K. Shanmugam's remarks in Parliament on Thursday that both countries have to honour the agreement.
Meanwhile, Singapore has opened its first plant to recycle industrial used water.
This water was previously treated to internationally-accepted standards and discharged into the sea. The new plant purifies it to a higher standard so it can be re-used by industries.
National water agency PUB said the plant can produce up to one million gallons of non-drinkable water per day, and the output will be used by companies on Jurong Island.
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