askST: How hygienic is tap water from HDB rooftop water tanks?

Reader Lim Mei asked ST: "How hygienic is tap water from Housing Board rooftop water tanks? Does PUB conduct checks? I sometimes drink water from the tap. Can bacteria breed in it?"

Housing reporter Janice Heng went to the national water agency, PUB, to find out.

It is safe to drink directly from the tap, says the PUB. And rooftop water tanks are checked at least once a year, to make sure that water quality is maintained.

A water tank installed on the rooftop of a HDB block in woodlands. PHOTO: ST FILE

Singapore's tap water is well within international guidelines set by the World Health Organisation, as well as the United States Environmental Protection Agency's drinking water standards.

It is suitable for drinking without further filtration or boiling.

In fact, on its website, the PUB discourages households from using filtration devices such as water filters and purifiers. If such filters are not cleaned or replaced regularly, bacteria could grow on them.

At PUB's waterworks, water from reservoirs is treated and disinfected.

"This frees the water of harmful bacteria and makes it wholesome and safe for consumption," said the PUB.

To ensure the quality and safety of the drinking water supply, the PUB monitors water quality across the entire system: from reservoirs and waterworks, to the distribution network of pipes, all the way to consumers' taps.

Each year, more than 400,000 water quality tests are conducted in PUB's accredited water quality laboratory.

"This includes water samples collected from taps in HDB flats and thus far all samples have passed," said the PUB.

As for HDB rooftop tanks, responsibility for them falls on Town Councils.

The PUB requires building owners, management corporations and Town Councils in charge of high-rise buildings with water tanks to engage a licensed water service plumber at least once a year to inspect the water tanks.

Where necessary, the licensed water service plumber must clean and disinfect the water tanks and certify them fit and safe for the storage of drinking water.

The plumber has to submit the certification, complete with water sample test reports, to the PUB.

Additionally, PUB carries out spot checks on these premises and samples water from these tanks.

"PUB takes a serious view of the safety of our water supply to customers," said the PUB.

"Should there be lapses, PUB will not hesitate to take enforcement."

If lapses are found, owners may face a fine of up to $10,000, a jail term of up to a year, or both.

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