Water

Country Water Action: Singapore
NEWater: From Sewage to Safe
December 2008

By Cezar Tigno
Web Writer

The world can learn a thing or two on water recycling from Singapore. Faced with diminishing freshwater sources, its national water agency, the Public Utilities Board (PUB), has tapped an unlikely resource—used, dirty, down-the-toilet-bowl, sewage water.

Using reverse osmosis technology, Singapore’s scientists have perfected the process of transforming sewage water into new, clean, safe drinking water. And since every corner of this bustling city is connected to a single sewerage system, Singapore will never run out of sewage water as long as its residents keep flushing.

Aptly branded NEWater, this reclaimed or recycled water is one of Singapore's “four national taps” or freshwater sources providing 7% of the country’s water demands. The other taps are:

• Local catchments, providing 50% of water needs
• Imported water from Johor, Malaysia, supplying 33% of water needs, made available through a 1961 agreement, and pumped through pipelines across the two-kilometer causeway separating the two countries
• Desalinated water, or converted seawater, addressing 10% of water needs¹

NEWater is a product of stringent purification and treatment processes capable of making sewage water clean, clear, and sparkling. PUB has even dared put NEWater into plastic bottles for public consumption.

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Singapore is now a global city—a prime destination of tourists, world entrepreneurs, and hopeful migrants from its Asian neighbors since its successful emergence as an international financial hub after the 1997 Asian Financial Crisis. Its 4.5 million people consume about 300 million gallons of water per day. The lack of water in this small, multi-cultural, city-state could have serious repercussions. It was a good thing, then, that the country foresaw its freshwater sources problem as early as the 1970s.

PUB built a pilot water reclamation plant in 1974, but implementation plans were shelved because of huge costs and unreliable technology. It wasn’t until 1998 that the project was revived through a joint initiative between PUB and the Ministry of Environment and Water Resources.

The 1998 Singapore Water Reclamation Study (or NEWater Study) clinched the deal on NEWater as a raw water resource to supplement the country’s water supply. With the agreement with Malaysia expiring in 2011 and water demands expected to rise to 400 million gallons a day by 2012, the development of NEWater is very timely.

Since 2003, four NEWater plants have been established, capable of meeting 15% of the country’s water needs. By 2010, NEWater can meet 30% of water needs as the fifth and largest NEWater plant becomes operational.

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Singapore’s scientists are by no means miracle workers. It took three decades of research and hard work to perfect a multiple barrier water reclamation process.

The conventional wastewater treatment process serves as the first barrier, removing sludge and much of the solid contents of sewage water. Singapore’s six Water Reclamation Plants that use the activated sludge process do the initial dirty job. Much of the treated water produced by these plants may already be used by some industries or for other nonpotable uses. A great portion of this treated used water undergoes the NEWater production process, broken down as follows:

1. Microfiltration, where treated, used water passes through fibers that work as microscopic filters, blocking the smallest of particles up to 0.2 microns in size. At this stage, suspended solids, most colloidal particles, bacteria, and protozoa are removed and turbidity is lowered to ensure a consistently good quality feed water and prevent clogging in the next stage.
2. Reverse Osmosis, which involves applying pressure for water to flow through a semi-permeable membrane that removes inorganic substances like heavy metals, nitrate, chloride, and sulfate, and organics such as disinfection by-products, aromatic hydrocarbons, pesticides, as well as viruses. The RO membrane has a pore size of 0.0001 microns and through this process, 95 percent of total dissolved solids can be removed.
3. Ultraviolet Disinfection,which serves as a safety measure to remove any bacteria or viruses that slipped through reverse osmosis, ensuring water purity. Some alkaline chemicals are added to restore the water’s pH balance making it safe for drinking.

Water reclamation, as a practice backed by solid scientific principles, has been around since the 1930s, with the first water reclamation plant built in California. However, reclaimed water has only been used either for nonpotable purposes, such as for agriculture, irrigation, and manufacturing, or for indirect potable use through injecting the water back to groundwater aquifers or catchments. In Singapore, NEWater was mainly used in wafer fabrication plants and other industries.

The process and the technology, however, continued to evolve and can now create safe water for drinking. US Military operations in the Middle East, for instance, relied on similarly-functioning devices called the ROWPUs (Reverse Osmosis Water Purification Units), which provided the US Army and Marine Corps their daily water needs in the desert.

But the country-wide application in Singapore is the first of its kind.

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NEWater now holds Singapore’s water future. PUB has started adding NEWater into its reservoirs at about 1% of total daily consumption following an evaluation by an Expert Panel from the National University of Singapore that gave the go-signal for NEWater’s indirect potable use. PUB plans to increase this to about 2.5% of total daily consumption by 2011.

Yaacob Ibrahim, Singapore’s Minister for Environment and Water Resources, assured the public of NEWater’s safety. “PUB has in place a water quality monitoring program to ensure that NEWater and tap water supplied by PUB are well within international drinking water standards, including those of WHO,” the Minister said.

With NEWater, Singapore has not only found use for its unlimited sewage water; it has also secured safe drinking water for the entire country.

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• Water Champion: Harry Seah on Making the Undrinkable Drinkable
• View the NEWater production process presentation.*
• Visit the PUB website.*
• Read the Singapore Straits Times article on Asia can tap S'pores water expertise
• Read the Singapore Straits Times article on Assurance on NEWater.*
• Singapore Water Action: Technology Turns Water Weakness into Strength.
• Read the Clean, Green and Blue: Singapore's Journey Towards Environmental and Water Sustainability Book.*

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¹ Figures as of 2007.
* This link takes you outside the ADB website. Please use the back button to return to ADB.org.