From toilet to tap

Singapore leads the way in water recycling but potential health risks are raising questions about the technique’s future

Christiane Oelrich
September 9, 2014
From toilet to tap

Millions of people do not have enough potable water, with the problem particularly acute in large urban centres such as the city-state of Singapore where there are no lakes to utilise.

Singapore believes the solution is to recycle sewage. Not surprisingly, the technology’s proponents first have to overcome major public concerns that the introduction of pre-used water into drinking supplies is a palatable, cost-effective alternative to measures such as desalination.

A young girl wrinkles her nose in disgust before taking a sip from a colourful bottle filled with NEWater, Singapore’s brand of recycled water. She sighs with relief after a swallow: “It doesn’t taste of anything.”

The water company invites tests at its visitor centre.

Singapore is running a public-awareness campaign on water and water-related issues, not least the long-term sustainable management of water resources. It won the United Nations ‘Water for Life’ Best Practices Award this year for its public communications and education efforts.

“Use every drop of water more than once,” is the motto of the national water agency, which is a world leader in the technology of introducing recycled water into drinking supplies.

Situated almost on the equator, Singapore is blessed with large amounts of rainfall, but lacks space for water reservoirs, meaning the option of water recycling is taken more seriously than elsewhere.

Public acceptance of the controversial concept, however, is another matter entirely. “Rain is also nothing more than recycled water,” said a tour guide at the NEWater visitor centre.

Most of the recycled water is not re-introduced into Singapore’s drinking water supplies, but is instead used by the semi-conductor industry and air-conditioning systems installed in public buildings.

Google Images Huaiwei
Photo: Google Images / Huaiwei

However, a small percentage is pumped into drinking water reservoirs. Bottled water from the recycling company can only be obtained at the NEWater visitor centre.

Singapore began working on recycling water in 2003, and now a third of the waste water produced by its 5.7 million inhabitants is treated in this way. A 48-kilometre network of tunnels has been constructed to transport the sewage from residential areas to huge treatment facilities where 273,000 cubic metres of NEWater is produced each day.

The water is purified by passing through micro-filters and membranes. Apart from this, it is also irradiated with ultraviolet light. “If you imagine the water molecules that pass through the membranes being as large as tennis balls, then an oestrogen hormone would be the size of a football by comparison,” the guide at the NEWater centre explained.
“A virus would be the size of a truck and bacteria as big as a house. None of these can make their way through the fine membrane.”

Water is a scarce commodity across much of the globe, with four billion people having to survive without adequate access to clean drinking water.

The problem has been exacerbated by the migration of populations from rural areas to ever-larger metropolitan centres.

A seawater desalination plant needs three times as much energy to produce one litre of drinking water as the NEWater production method, which has led Orange County in California to follow in Singapore’s footsteps.

Australians are also being encouraged to embrace the NEWater concept, but deep public scepticism and fears of health risks have so far kept it off the political agenda.

However, Tim Fletcher, director of the Institute of Sustainable Water Resources at Monash University in Melbourne, believes it is only a matter of time before parts of Australia begin recycling wastewater for use in the domestic supply.

“The interesting thing is the Australian standard for recycled water is stricter than the Australian standard for the drinking water supply,” Fletcher told Australia’s ABC broadcaster.

“In other words, if we’re going to drink recycled water, we can be assured that the quality actually will be of equal or higher quality than what we get in our drinking water supply, because the law requires it to be so.”

On the other hand, Professor Peter Collignon, an infectious diseases physician and microbiologist at the Australian National University believes the concept is “irresponsible”, due to the risk of the spread of disease.

“It should be a last-resort option for many reasons, but especially because of the potential catastrophic public health implications if something in this complex and very high-risk process goes wrong.”

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