Water with pandan scent isolated, local production ramped up: PUB

Singapore has raised the local production of water to meet demand, after part of the water supply from Malaysia had to be "isolated" following reports from households here about an unusual scent of pandan in boiled tap water.

The cause of the scent is an organic compound known as tetrahydrofuran (THF), which is commonly used as an industrial solvent.

National water agency PUB said its investigations traced the source of the issue to water imported from Malaysia.

In a Facebook update yesterday, PUB said it has "isolated" the affected water, and that production has been increased at waterworks in Singapore.

"We also took extra precaution to flush out the affected network pipes and water tanks, and replenished them with water produced by our local waterworks," said PUB, although it did not provide details on how much local water production was boosted on Wednesday.

The Johor River in Malaysia is a major source of water for Singapore, but the Republic can also count on its three other taps - desalination, treatment of used water, as well as rainwater collected in Singapore's 17 reservoirs.

The Straits Times reported on Wednesday that a number of households in Singapore - such as in Pasir Ris, Yishun and Tampines - had noticed an unusual scent of pandan in boiled tap water.

The scent was not apparent until the water was boiled.

Laboratory tests had found trace levels of less than 10 parts per billion of the THF organic compound in the water supply.

This concentration is equivalent to dissolving two tablespoons of a substance in an Olympic-size swimming pool, PUB said.

It added that THF is highly soluble and has a low boiling point but in this case, because the amounts present in the water were so minuscule, it would have no adverse impact on health.

In yesterday's update, PUB said customers should not detect any smell from tap water freshly supplied from Singapore's waterworks.

"Any smell could be due to remnant water remaining in house pipes," said the agency.

"This can be resolved by running the taps for about five minutes to flush out the water."

PUB said it will continue to monitor water quality closely.

Professor Shane Snyder, executive director of the Nanyang Environment and Water Research Institute at the Nanyang Technological University, said at the "extremely low concentrations reported", THF is very difficult to detect.

THF is unique because the human nose can detect minute concentrations, better than most analytical devices, he said.

"The current generation of on-line sensors are not able to detect such a low amount of a compound like THF, though this is a major area of research for my team at NTU," Prof Snyder said.

He added that the incident showed Singapore's ability to respond quickly and adequately to contamination events.

"It is important to continue to invest in research that can better detect such contamination, but still, the response from PUB is very impressive to me and my colleagues," said Prof Snyder.

LISTEN TO GREEN PULSE PODCAST

Join ST's WhatsApp Channel and get the latest news and must-reads.

A version of this article appeared in the print edition of The Straits Times on July 24, 2020, with the headline Water with pandan scent isolated, local production ramped up: PUB. Subscribe