Ensuring Safety of Tap Water After Leakage of Chemical Compound Found

Mr Zhulkarnain Abdul Rahim asked the Minister for Sustainability and the Environment in light of the Nanyang Environment and Water Research Institute (NEWRI) study regarding a chemical compound which could be leaking in minute traces into the tap water (a) what are the steps that PUB will take to ensure the safety of tap water post-treatment; (b) what is the public outreach to allay any concerns on the safety of tap water; and (c) whether the Ministry will be studying the outcome of the research by NEWRI, once concluded, to explore any follow-up actions.

The study by the Nanyang Environment and Water Research Institute (NEWRI) sought to understand the highest potential for contaminants to form in drinking water from the leaching of polymer additives by performing "stress" tests under experimental conditions, such as higher chlorine concentrations and extended contact time between tap water and the plumbing fittings. These conditions are not representative of Singapore's water distribution system. The concentration of chlorine in our tap water is usually about half of the four milligrammes per litre concentration used in the study. The contact time between tap water and the plumbing fittings is also a matter of seconds, compared to the two-week period used in the study. PUB's tests of our potable water under actual conditions indicate that the risk of formation of these contaminants is very low.

PUB has a comprehensive and robust sampling and monitoring programme that runs from source to tap. It ensures that water supplied is safe for consumption. This includes conducting over 500,000 tests annually, covering a range of physical, chemical, radiological and microbiological parameters, such as pH, chlorine and Escherichia coli.

PUB welcomes NEWRI's research, which helps to improve our understanding of potential contaminants of concern. PUB has been actively engaging the research team to further understand the implications of the study findings on public health in the Singapore context and will continue keeping abreast of the research and developments in international benchmarks in this area.