Water supply and sanitation in Singapore
|Singapore: Water and Sanitation|
|Access to an improved water source||100% (2012) |
|Access to improved sanitation||100% (2012) |
|Continuity of supply (%)||100|
|Average urban water use (liter/capita/day)||153 (2012) |
|Average urban domestic water and sewer tariff per m3||US$1.88 (S$2.38, 2012, for a consumption of 20m3 per month) |
|Share of household metering||100%|
|Annual investment in water supply and sanitation||USD 609 million (2010), or USD 117/capita/year |
|Financing||Self-financing through retained earnings, debt financing through bonds and project finance for desalination|
|National water and sanitation company||Yes, the Public Utilities Board (PUB)|
|Water and sanitation regulator||None|
|Responsibility for policy setting||Ministry of the Environment and Water Resources|
|Number of urban service providers||1|
Water supply and sanitation in Singapore is characterised by a number of achievements in the challenging environment of a densely populated island. Access to water is universal, affordable, efficient and of high quality. Innovative integrated water management approaches such as the reuse of reclaimed water, the establishment of protected areas in urban rainwater catchments and the use of estuaries as freshwater reservoirs have been introduced along with seawater desalination in order to reduce the country's dependence on water imported from neighboring country, Malaysia.
Singapore's approach does not rely only on physical infrastructure, but it also emphasizes proper legislation and enforcement, water pricing, public education as well as research and development. In 2007 Singapore's water and sanitation utility, the Public Utilities Board, received the Stockholm Industry Water Award for its holistic approach to water resources management.
- 1 History
- 2 Water sources and integrated management
- 3 Sanitation
- 4 Stormwater management
- 5 Water use, conservation and efficiency
- 6 Responsibility for water supply and sanitation
- 7 Research and development
- 8 Financial aspects
- 9 See also
- 10 References
- 11 External links
Local water supply and first water imports during colonial time (until 1973)
The history of common water supply in Singapore began with the construction of the MacRitchie Reservoir, which was built by the British in 1868. The Lower Peirce Reservoir and the Upper Seletar Reservoir were completed in 1910 and 1940 respectively, in order to supply the rapidly modernising colonial city with sufficient water. In 1927 the municipal leadership of Singapore and Sultan Ibrahim of the state and territories of Johor in neighboring Malaya signed an agreement that allowed Singapore to rent land in Johor and use its water for free. In 1932 a pipeline to transport the raw water to Singapore was inaugurated. Another pipeline was built to return a smaller quantity of treated water to Johor. During the Battle of Singapore in 1942 the Causeway that links Singapore with Malaya and that carries the pipeline was blown up by retreating British troops, thus unintentionally destroying the pipeline, which left Singapore with water reserves that could last at most two weeks. According to Lee Kuan Yew, this was one of his motives to envision water self-sufficiency for Singapore later when he became the city-state's Prime Minister.
Expansion of water imports from Malaya and of local reservoirs (1965-1997)
After the war, Singapore continued to grow rapidly and more water was needed to sustain the city’s growth. The 1927 agreement was superseded by two new agreements signed in 1961 and 1962 between the independent federation of Malaya and the self-governing British territory of Singapore. They foresaw the payment of a water rate in addition to the rent for the land.
Under these agreements Singapore built two water treatment plants in Singapore and a new, expanded pipeline from Johor. Singapore also supplied treated water to Johor far below the cost of treating the water. At the time of the agreements it was expected that Singapore would become part of Malaysia, as it did for a brief period beginning in 1963.
When Singapore separated from Malaysia in 1965, then Malaysian Prime Minister Tunku Abdul Rahman said that "If Singapore’s foreign policy is prejudicial to Malaysia’s interests, we could always bring pressure to bear on them by threatening to turn off the water in Johor". Malaysians point out that this statement should be seen in context that Malaysia and Indonesia were engaged in a confrontation at the time and that the remark referred to the possibility of Singapore siding with Indonesia.
This was another motive for Singapore to further develop its local water resources, according to Lee Kuan Yew. Therefore, in parallel to the gradual expansion of water imports from Johor the Public Utilities Board, created in 1963, embarked on the construction of more water schemes inside Singapore. They included the damming of river estuaries to allow for greater storage volumes. For example, the Kranji-Pandan Scheme, completed in 1975, included the damming of the estuary of the Kranji river and the construction of a reservoir at Pandan. In the same year, the Upper Peirce Reservoir was completed. As part of the Western Catchment Scheme, completed in 1981, another four rivers were dammed.
In 1983, a dam was built across the estuary of the Seletar River to form the Lower Seletar Reservoir. But these amounts were still not sufficient, and seawater desalination was too expensive at the time to be considered. Singapore was thus interested in building a dam on the Johor River in Malaysia and an associated new water treatment plant. After six years of difficult negotiations, the Prime Ministers of Singapore and Malaysia signed a Memorandum of Understanding in 1988 paving the way for an agreement in 1990 with Johor that allowed the construction of the dam.
Failed Water Negotiations with Malaysia (1998-2002)
In 1998 Singapore began new negotiations with Malaysia to extend its water agreements beyond 2011 and 2061 respectively. In return, Malaysia initially asked to increase the raw water price to 60 sen per 1,000 imperial gallons (4,500 L), corresponding to 4 US cents per cubic meter. This price was still much lower than the cost of desalinated seawater or of NEWater. However, in 2002 Malaysia asked for a much higher price of 6.4 Malaysian Ringgit per 1,000 imperial gallons (4,500 L) (US$0.45 per cubic meter), arguing that Hong Kong paid the equivalent of 8 Malaysian Ringgit per cubic meter for water from China.
The new price proposed by Malaysia was close to the price of desalinated water. The government of Singapore said that Malaysia had no right to alter the price of water. It further clarified that the price paid by Hong Kong included payment for substantial infrastructure provided by China, while Malaysia provided only access to raw water and the infrastructure necessary to convey the water inside Malaysia was entirely paid for by Singapore. Singapore finally refused to accept a higher price and decided to give up on its goal to extend the agreements beyond 2061. Instead, the country decided to achieve self-sufficiency in its water supply before 2061 and the negotiations ended in 2003 without result.
Towards Water Self-Sufficiency (since 2002)
While the negotiations were ongoing Singapore already prepared for greater water self-sufficiency through an integrated water management approach including water reuse and desalination of seawater. In 1998, the government initiated a study, the Singapore Water Reclamation Study (NEWater Study), to determine if reclaimed water treated to potable standards was a viable source of water. In order to facilitate the new integrated approach, the Public Utilities Board, which had previously been in charge of water supply only, was given the responsibility for sanitation as well in 2001. Previously sanitation had been under the direct responsibility of the Ministry of Environment. The new policy was called the "Four Taps": The first and second taps were local water catchments and water imports.
In 2002 Singapore commissioned its first reclaimed water plant, thus opening a "Third Tap". This was done carefully, after a monitoring period of two years to ensure safe water quality. There was also an active marketing campaign that included the opening of a visitor center, the sale of NEWater in bottles and the Prime Minister drinking a bottle of NEWater in front of the cameras. In 2005 Singapore opened its first seawater desalination plant, the "Fourth Tap". In the meantime it also further expanded its reservoirs, the "First Tap". Today's largest reservoir, the Marina Bay reservoir, was inaugurated in 2008. It is located in the estuary of a river that has been closed off by a barrage to keep the seawater out. Two similar barrages were completed in July 2011, forming the Punggol Reservoir and the Serangoon Reservoir. When the 1961 water agreement with Malaysia ended in August 2011, Singapore could thus afford to let it expire.
Furthermore, Singapore has become a global water research and technology hub with active support from the government.
Singapore wants to be water self-sufficient before the 1962 long-term water supply agreement with Malaysia expires in 2061. According to analysis by the Institute of Southeast Asian Studies in 2003, Singapore would already be water self-sufficient by 2011 and "the 'water threat' is less than what it seems to be". However, according to official forecasts water demand in Singapore is expected to double from 380 to 760 million gallons per day between 2010 and 2060. The increase is expected to come primarily from non-domestic water use, which accounted for 55% of water demand in 2010 and is expected to account for 70% of demand in 2060. By that time water demand is expected to be met by reclaimed water at the tune of 50% and by desalination accounting for 30%, compared to only 20% supplied by internal catchments.
Water sources and integrated management
The water resources of Singapore are especially precious given the small amount of densely settled land. Singapore receives an average of 2,400mm of rainfall annually, well above the global average of 1,050mm. The constraint is the limited land area to catch and store the rainfall, and the absence of natural aquifers and lakes. Therefore, Singapore relies on four water sources, called "the four taps":
- rainfall, collected in artificial reservoirs that collect water from carefully managed catchment areas (200-300 million gallons per day, depending on rainfall),
- Imported water from Malaysia (up to 250 million imperial gallons (1,100,000 m3) per day, according to the 99-year agreement signed in 1962, plus an additional quantity under the 1990 agreement),
- Reclaimed water (producing what is called NEWater) (up to 115 million imperial gallons (520,000 m3) per day, officially only "30% of demand"), and
- Seawater desalination (up to 50 million imperial gallons (230,000 m3) per day, officially only "10% of demand").
This "four tap" strategy aims to reduce reliance on supply from Malaysia by increasing the volume supplied from the three other sources, or "national taps". Since water demand in 2011 was 380 million imperial gallons (1,700,000 m3) per day, Singapore could actually already have been water self-sufficient in 2011 except in years of very low rainfall. The official figures downplay the share of reclaimed and desalinated water in water supply, and thus the ability of the country to be self-sufficient. However, the Chairman of PUB admitted in 2012 that water self-sufficiency could be achieved well before the target year of 2061.
In Singapore, water management is closely integrated with land management. The latter is tightly controlled in order to prevent any pollution of water resources through sewage, sullage or other sources of pollution. The management of water supply, sanitation and stormwater drainage is managed by a single agency, the Public Utilities Board, in an integrated and coordinated manner.
Water from catchment areas
Two thirds of the country's surface area are classified as partly protected catchment areas with certain restrictions on land use, so that the rainwater can be collected and used as drinking water. As of 2012, surface water was collected in 17 raw water reservoirs. Singapore's oldest reservoirs - MacRitchie, Lower Peirce, Upper Selatar as well as the more recently built Upper Peirce Reservoir - are all located in the Central Catchment Nature Reserve, a protected area that has been reforested to protect the water resources and act as a "green lung" for the city. The larger reservoirs, however, have been built after independence and are located in river estuaries that have been closed off by barrages.
Singapore imports water from Johor state in Malaysia through a pipeline that runs along a 1 km bridge, the Johor–Singapore Causeway, that also carries a road and a railway. As of 2009, imported water had been reduced from 50% previously to 40% of total consumption. After the expiry of a 1961 water agreement between Malaysia and Singapore in 2011, two agreements are in force now. One was signed in 1962 and another one in 2000. Both will expire in 2061. Under the first agreement the price of raw water is set at a very low level of 3 Malaysian sen per 1,000 imperial gallons (4,500 L), corresponding to about 0,2 US cents per cubic meter.
Under this agreement Singapore is entitled to receive up to 250 million imperial gallons (1,100,000 m3) per day, corresponding to 66% of its water use of 380 million imperial gallons (1,700,000 m3) in 2011. Furthermore, under the 1990 agreement Singapore is entitled to receive an additional unspecified quantity of water from the Linggui dam in Malaysia at a price that is higher than under the 1960 agreement. The actual amount of water imported is much lower than the entitlement: Based on the 40% share quoted above, water imports in 2011 are about 150 million imperial gallons (680,000 m3).
NEWater is the brand name given to ultra-pure water that is produced from reclaimed water. Wastewater, which is called used water in Singapore, is treated in conventional advanced wastewater treatment plants that are called reclamation plants in Singapore. The effluent from the reclamation plants is either discharged into the sea or it is further treated in NEWater plants using dual-membrane (via microfiltration and reverse osmosis) and ultraviolet technologies.
The quality of NEWater is monitored by, among others, an international panel of experts. The quality of NEWater exceeds WHO standards for drinking water. In 2012, there were four NEWater factories, located at the Bedok, Kranji, Ulu Pandan and Changi next to five water reclamation plants.
|Plant name||Date of commissioning||Current capacity||Operator|
|Bedok||2002||19 million imperial gallons (86,000 m3)||PUB |
|Kranji||2002||12 million imperial gallons (55,000 m3)||PUB |
|Seletar||2004||Decommissioned in 2011||PUB |
|Ulu Pandan||2007||33 million imperial gallons (150,000 m3)||Keppel Seghers |
|Changi||2010||50 million imperial gallons (230,000 m3)||Sembcorp |
Most of the NEWater is used by industries for non-potable uses such as wafer fabrication. The rest is fed into nearby reservoirs. As of 2008, according to PUB NEWater was able to meet 30% of Singapore's water requirements. The high purity of the water has actually allowed industries to reduce their costs. With the construction of the Deep Tunnel Sewerage System the decentralized water reclamation plants and NEWater factories are expected to be gradually closed and replaced by the single, much larger water reclamation plant and NEWater factory at Changi at the Eastern end of Singapore Island. The Bedok reclamation plant was the first one to be decommissioned in 2009, followed by the Seletar plant in 2011. The Bedok NEWater plant, however, continued to operate, while the Seletar NEWater plant was decommissioned along with the reclamation plant. The Kranji, Ulu Pandan and Bedok reclamation plants had been upgraded in 1999-2001, making them more compact so that they needed less land and covering them for odor control in order to make nearby land more valuable.
On 13 September 2005, the country opened its first desalination plant, SingSpring Desalination Plant, in Tuas at the southwestern tip of Singapore Island. The S$200 million plant, built and operated by Hyflux, can produce 30 million imperial gallons (140,000 m3) of water each day and meets 10% of the country's water needs. The bid to build and operate Singapore's second and largest desalination plant, Tuaspring Desalination Plant, with a capacity of 70 million imperial gallons (320,000 m3) per day, also located at Tuas, was launched in June 2010. Hyflux won the contract in April 2011, and the plant began operations two years later in 2013 . Together, desalinated water from SingSpring and Tuaspring can meet up to 25% of Singapore's current water needs.
The government has identified five coastal sites for future plants, with the objective of bringing the installed capacity to one million m³ per day, so that desalination will be able to meet up to 25% of Singapore's future water demand by 2060.
Until 2010, wastewater in Singapore was collected through a sewer system that included 139 pumping stations that pumped water to six wastewater treatment plants. These pumping stations and plants are to be gradually decommissioned while a new system, the Deep Tunnel Sewerage System (DTSS), becomes operational. The Changi Water Reclamation Plant, the heart of the first phase of the DTSS, was opened by Prime Minister Lee Hsien Loong in June 2010.
The first phase of the DTSS consists of a 48-km long deep tunnel sewer that runs 20 to 55 metres below ground, channels used water to the Changi Water Reclamation Plant at the Eastern end of the island. The plant had an initial capacity of 176 million imperial gallons (800,000 m3) per day. Most of the treated used water is discharged into the sea through an outfall, while some of it is further purified into NEWater. The deep tunnel works entirely by gravity, eliminating the need for pumping stations, and thus the risks of used water overflows. At one-third the size of conventional plants, the Changi Water Reclamation Plant is designed to be compact. Centralisation of used water treatment at Changi also allows for economies of scale. In a second phase of the DTSS, the deep tunnel system is to be expanded to the entire island, with a second wastewater treatment plant at Tuas at the Western end of the island.
The stormwater drainage system in Singapore is completely separated from the sewer system. It consists of 7,000 km of public roadside drains and about 1,000 km of major canals and waterways that are regularly cleaned of debris and maintained by private companies under performance-based contracts with PUB. This system has reduced the flood-prone area from 3,200 hectares in the 1970s to about 49 hectares today despite increased urbanization, which usually would have resulted in more floods. PUB plans to further reduce flood prone areas to 40 hectares by 2013. In the 1960s and 1970s widespread flooding was common in Singapore, especially in the city centre, which is built on relatively low-lying land. Nevertheless, flash floods caused by unusually heavy rains and blocked drains caused damage in 2010 and 2011.
Water use, conservation and efficiency
There have also been campaigns to urge people to conserve water, reducing consumption from 165 litres per person per day in 2003 to 155 litres in 2009. The target is to lower it to 140 litres by 2030. Public education was an important instrument to promote water conservation. For example, a Water Efficiency Labeling Scheme for taps, showerheads, toilets and washing machines was introduced so that consumers could make informed choices when making purchases. Also, the tariff structure was modified. While tariffs historically included a cross-subsidy from industries that paid a higher price to residential users that paid a lower price for social reasons, this policy was ended and residential users were charged a tariff that covers the full costs of supply. The level of water losses - more precisely defined as non-revenue water - is one of the lowest in the world at only 5%.
Responsibility for water supply and sanitation
Within the government of Singapore the Ministry of the Environment and Water Resources is in charge of policy setting for water and sanitation. The Public Utilities Board, a statutory board under the Ministry, is in charge of providing drinking water as well as of sanitation and stormwater drainage. It also monitors compliance of potential polluters on the basis of the Sewerage and Drainage Act. PUB this is both a service provider and a regulator, but its regulatory role only encompasses other entities. The National Environment Agency monitors PUB's compliance with environmental as well as drinking water quality standards on the basis of the Environmental and Public Health Act. Legislation is effectively implemented, with heavy fines, and the various agencies in charge of water work together in a coordinated manner under a common framework.
Research and development
In 2006, the Singapore government identified water as a new growth sector and committed to invest S$330 million over the following five years in order to make Singapore a global hub for water research and development. PUB has an active research and development program that includes upstream research, pilot projects and demonstration projects. An Environment and Water Industry Development Council (EWI) has been establish to support, together with the National Research Foundation, a Strategic Research Programme on Clean Water.
Leading Japanese companies such as Toshiba and Toray have established water research centers in Singapore. Singapore is home to over 70 local and international water companies and 23 research and development centers working on about 300 projects valued at $185 million. Furthermore, the Lee Kuan Yew School of Public Policy at National University of Singapore established an Institute of Water Policy in 2008. Also since 2008, the city-state has hosted the Singapore International Water Week, a key event for the global water industry.
Tariffs. Water and sewer tariffs in Singapore are set at a level allowing cost recovery, including capital costs. Water and sewer tariffs were raised substantially in the late 1990s, so that the average monthly domestic bill including taxes increased from S$13 in 1996 to S$30 in 2000. The sewerage tariff (called "waterborne fee") is S$0.30/m3 for domestic users plus a fixed tariff of S$3 per "chargeable fitting" per month. The water tariff includes a conservation tax set at 30% that increases to 45% for domestic consumption above 40 m3 per month. A general service tax of 7% is added to the bill. As of 2012, a household consuming 20 m3 per month and that has three "chargeable fittings" faces a water bill of S$32.5 per month and a sewer bill of S$15 per month, both including all taxes. The total of S$47.5 (USD 37.7) per month corresponds to S$2.38/m3 (US$1.88/m3). Industrial water tariffs are set lower at S$0.52/m3. Water and sewerage tariffs are lower than tariffs in some European countries such as in Germany where the average water and sewer tariff including taxes was Euro 3.95 per m3 in 2004.
Investment. In the financial year 2010 PUB undertook investments of S$411 million (USD 290 million) in its own assets, mainly for water supply and NEWater, and S$451 million (USD 319 million) for assets belonging to the government, mainly for sanitation and stormwater drainage. This corresponds to annual investments of USD 117 per capita, which is higher than in the United States where the corresponding figure is USD 97.
Financing. In 2005 PUB issued for the first time a bond, raising S$400 million, to finance part of its investment program. Since then, bonds have been issued regularly, including a S$300 million bond with a maturity of 20 years in 2007. During the financial year 2010, PUB Group received an operating grant of S$185 million to fund the operation and maintenance of the stormwater drainage network and operating costs of certain water infrastructure assets such as the Marina, Serangoon and Punggol Reservoir schemes.
- WHO/UNICEF:Joint Monitoring Program for Water Supply and Sanitation:Data resources and estimates - Introduction, accessed on July 21, 2012
- Public Utilities Board:Conserve, accessed on August 22, 2010
- Public Utilities Board:Water tariff, accessed on July 16, 2012
- Financial Report 2010/11. "Financial Review for Financial Year 2010" (PDF). Public Utilities Board. pp. 54–55. Retrieved 7 June 2012.
- Ivy Ong Bee Luan (2010). "Singapore Water Management Policies and Practices". International Journal of Water Resources Development 26 (1): 65–80. doi:10.1080/07900620903392190. Retrieved 20 July 2012.
- Stockholm International Water Institute:Stockholm Industry Water Award:PUB Singapore
- "Singapore’s Water Cycle Wizardry," by Sandra Upson, IEEE Spectrum, June 2010, retrieved on August 9, 2012
- Valerie Chew: Singapore-Malaysia water agreements, Singapore Infopedia, retrieved on June 7, 2012
- Development of Water Supply Infrastructure: MacRitchy Reservoir History, retrieved on June 7, 2012
- quoting Professor Nur Anuak (6 January 2003). "History of water - according to Utusan Malaysia, in: Malaysia to stop purchasing treated water from singapore". Retrieved 11 August 2012.
- The Star:WATER: The Singapore-Malaysia Dispute: THE FACTS
- Cecilia Tortajada and Kimberly Pobre:The Singapore–Malaysia water relationship: an analysis of the media perspectives, Hydrological Sciences Journal, July 2011
- BBC:Malaysia raises water stakes, 15 February 2003, retrieved on July 21, 2012
- Baradan Kuppusamy Water war makes small splash, Asia Times, 1 August 2003
- Poh Onn Lee (2003, updated in July 2010). "The water issue between Singapore and Malaysia: No solution in sight?". Retrieved 11 August 2012. Check date values in:
- Bloomberg interview with Chew Men Leong, chief executive of PUB (30 July 2012). "Singapore To Meet Water Target Before Deadline: Southeast Asia". Retrieved 9 August 2012.
- PUB. "Four National Taps Provide Water for All". Retrieved 10 August 2012.
- PUB. "Local Catchment Water". Retrieved 15 July 2012.
- PUB. "Water Treatment". Retrieved 12 August 2012.
- "Key step to water adequacy". Straits Times. Archived from the original on June 27, 2009. Retrieved 2009-06-24.
- Valerie Chew:Singapore-Malaysia water agreements, Singapore Infopedia. This is based on an exchange rate of 3.11 Malaysian Ringgit per US dollar, as of August 11, 2012
- General Electric. "Bedok NEWater Factory" (PDF). Retrieved 10 August 2012.
- PUB. "PUB Expands NEWater Plants and Builds MBR Demo Plant, 15 September 2005". Retrieved 10 August 2012.
- PUB. "Seletar Water Reclamation Plant Decommissioned". Retrieved 10 August 2012.
- Channelnewsasia:NEWater to supply 30% of Singapore's water needs by 2011: PM, retrieved on August 10, 2012
- PUB. "NEWater". Retrieved 9 August 2012.
- Channelnewsasia:PUB awards contract for NEWater plant at Changi to Sembcorp, retrieved on August 10, 2012
- "2008 PUB Annual Report". Public Utilities Board. Retrieved 25 June 2009.
- PUB. "Water Reclamation Plants". Retrieved 9 August 2012.
- Dominique Loh. "PM Lee opens Asia's largest water desalination plant in Tuas". Channel NewsAsia.
- "Hyflux to build Singapore's biggest desalination plant". Straits Times.
- PUB Press Release (6 April 2011). "PUB and Hyflux sign Water Purchase Agreement for Singapore’s second and largest desalination project". Retrieved 9 August 2012.
- National Environment Agency:Deep Tunnel Sewerage System (DTSS), News Release, 22 January 2001, accessed on August 22, 2010
- "Milestones: Largest and most advanced water reclamation plant in Southeast Asia". Public Utilities Board. Retrieved 7 June 2012.
- "Drainage Maintenance". Retrieved 9 August 2012.
- PUB. "Managing Flash Floods: Overview". Retrieved 9 August 2012.
- Channelnewsasia.com (24 December 2011). "Managing flash floods is PUB's priority: CEO". Retrieved 9 August 2012.
- PUB:. "R&D Approach in PUB". Retrieved 19 July 2012.
- National Research Foundation. "Strategic Research Programmes: Environmental & Water Technologies". Retrieved 19 July 2012.
- Xinhua (5 July 2011). "Singapore to boost funding for water research, development". Retrieved 19 July 2012.
- EDB Singapore (11 April 2012). "Toshiba opens water treatment research centre in Singapore". Retrieved 19 July 2012.
- Toray (29 June 2010). "Inauguration of Toray Singapore Water Research Center - Toray's Water Treatment R&D Base in Singapore -". Retrieved 19 July 2012.
- PUB Annual Report 2011. "Partnering for Water". Retrieved 9 August 2012.
- Cecilia Tortajada (2006). "Water management in Singapore". International Journal of Water Resources Development 22 (2): 227–240. doi:10.1080/07900620600691944.
- Public Utilities Board. "PUB Bond, October 2007". Retrieved 7 June 2012.
|Library resources about
Water supply and sanitation in Singapore