askST: Could tap water to homes be contaminated by heavy metals from the pipes?

Reader Weijia Soon sent askST a query after a recent askST Q&A about the cleanliness of tap water from HDB rooftop tanks.

He wanted to know: "How does PUB ensure drinking water from the tap does not contain heavy metal contamination? I understand that checks on HDB water tanks are done regularly, but how about the pipes that bring water to individual homes?

"In particular, the very old estates with old piping can have heavy metals leaking into the water (such as in the recent HK cases). These are extremely harmful to our health, and of deep concern for pregnant women and babies."

Housing reporter Janice Heng took this concern to the national water agency, PUB.

There is no contamination of heavy metals in PUB water, said the agency.

Singapore's water distribution network does not use lead or lead jointing, explained the PUB.

Instead, the water supply travels through a network of corrosion-resistant pipes, such as cement-lined ductile iron pipes and copper pipes.

The PUB's water quality monitoring programme covers the entire system, from reservoir and waterworks, through the distribution network, all the way to the end customer's tap.

This monitoring of water quality includes older housing estates as well.

The PUB also has a systematic pipe replacement programme to replace older and leaky pipes within older housing estates.

"Overall, PUB conducts more than 400,000 quality tests on the water that we supply to our customers to ensure that our product is entirely safe and wholesome," said the PUB.

This includes testing for heavy metals such as lead.

So far, the PUB has not detected any contamination of heavy metals and lead in Singapore's water supply, including within older housing estates.

Furthermore, if pipes and fittings material are to be used in customers' premises for potable water - that is, drinking water - purposes, then they must comply with PUB standards and requirements.

Only after complying with such standards can they be advertised, displayed or offered for sale for potable water use.

In addition, lead pipes and fittings made of lead or lead alloy, including lead soldering alloy, are banned from being used in the potable water supply system.

More askST stories here.