SINGAPORE – A woman suspected to be involved in posting notices alleging that the water source in a Fernvale Road HDB block had been "heavily contaminated with poisonous substance" has been arrested. 

The Police said in a media update on Friday (Feb 9) night that the 40-year-old Singaporean was arrested under the mental health act, hours after the PUB sent out a statement denying the claims. 

Investigations against the woman are ongoing.

Member of Parliament (MP) Gan Thiam Poh, who is the adviser to the Sengkang South GROs, said on Saturday that he was pleased with how the community came together with the authorities to quickly track down the culprit.

"This is not something we will take lightly...(especially) when it comes to spreading rumours and causing panic, threatening peace and public order," said Mr Gan.

Mr Gan, who was alerted to the incident by a resident, told the authorities to take it seriously and "verify the claims, even though it is likely to be a prank."

Earlier on Friday, PUB wrote in a Facebook post that the notice was pasted on the doors of several units in Blk 406B Fernvale Road. The notice also urged residents to use bottled water for drinking and cooking.

The notice, which was written in English and Mandarin, alleged that the block's "water source is heavily contaminated with poisonous substance". It also urged neighbours to "cover all floor traps and sink holes when not in use as there is unidentified gas present". 

Refuting the notice, PUB said it had collected water samples from the block and tests showed the water quality to be "within normal range and safe for drinking".

"The public need not be alarmed," the agency added. "PUB is working closely with the Police to investigate the matter."

Mr Gan said that "agencies" and grassroots members have since spoken to the residents of the affected block to allay their fears.

Ms Vonne Yeo, a resident of Block 406B, told TODAY she only saw the notice on Friday, though her neighbour said she saw it at the lift lobby some two weeks back.

Concerned about the legitimacy of the notice, she flagged it to the police in a Facebook post on Friday evening and called up her town council. She had also “escalated” it to Mr Gan.

Ms Yeo said the Town Council sent a cleaner to remove the notices after she lodged the complaint.

The 40-year-old business process analyst said she was uncertain why someone would post such a notice.

“I did a check on my floor and out of six units, five had (the notices),” she said, adding that she heard residents on other floors had received similar notices.