Four National Taps

The Four National Taps, a term used by then Minister for the Environment Lim Swee Say in 2004, refer to the four sources that Singapore relies on for its water supply.1 They comprise water from local catchment, imported water, high-grade reclaimed water known as NEWater, and desalinated water.2 During the early days of Singapore’s independence in the 1960s and 1970s, the country depended on two of these sources – local catchment water and imported water from Malaysia.3 To improve national water security, the government began exploring alternative sources of water in the 1970s, eventually introducing NEWater and desalinated water in the early 2000s.4

Although Singapore receives abundant rainfall annually, it lacks groundwater and natural freshwater bodies. Singapore’s compact land size also limits the amount of land that can be allocated to capture and store rainwater. Additionally, drastic changes in weather conditions may create water shortages. A drought, for instance, led the Singapore government to impose water rationing nationwide in the early 1960s.5

Amidst such challenges, the water needs of Singapore’s growing population and expanding economy have continued to increase, with overall water consumption rising more than six-fold since 1965.6

To meet the country’s growing demand for water, a tightly integrated water management system based on three strategies has been used: collect every drop of water; reuse water endlessly; and desalinate more seawater.7

First National Tap – water from local catchment
In the 1960s, the MacRitchie, Peirce and Seletar reservoirs were Singapore’s main domestic sources of water. As these were insufficient to meet the country’s growing water needs, Singapore also imported water from Malaysia. To increase the local supply of water, the Public Utilities Board (PUB) expanded the capacities of Seletar Reservoir and Peirce Reservoir. This expansion was completed in 1969 and 1975 respectively.8

The MacRitchie, Peirce and Seletar reservoirs are located in protected catchments, where their natural states are preserved as no development is allowed. However, in the 1970s, as the population and economy expanded, land was allocated to meet the growing demand for housing and industry. Competing demands for land thus necessitated new methods of increasing the number of water sources. A Water Planning Unit was set up in 1971 to examine such methods, one of which was the use of unprotected catchments in which only restricted development (in the form of residential estates and industries that did not rely on chemicals) was allowed.

Under the 1972 Water Master Plan, potential catchment areas and reservoirs to collect rainwater to boost local water supply were identified, and a plan was devised to guide the long-term development of water resources. The first unprotected catchments were thus created between 1975 to 1981 by damming the Kranji, Pandan, Murai, Poyan, Sarimbun and Tengeh rivers to create new reservoirs.9

Across the country, the government also cleaned up polluted waterways so that these could function as water catchments for harvesting rainwater. The most significant and ambitious project was the clean-up of the highly polluted Singapore River and Kallang Basin, which began in 1977 and was completed in 1987. Together, these two catchments made up 30 percent of Singapore’s land area in the 1970s.10 Today, they form part of the urban catchment that feeds into Singapore’s first city reservoir, Marina Reservoir. As of 2018, Singapore has 17 reservoirs islandwide, with catchment areas making up two-thirds of the country’s land area.11 PUB aims to increase the size of water catchment areas to 90 percent of Singapore’s land area by 2060.12

Second National Tap – imported water
The Second National Tap dates back to colonial times, when Singapore started importing water from Johor, Malaysia, through an agreement signed in 1927.13 This agreement is no longer in force.14 After Singapore achieved self-government, it signed a new agreement with Johor in 1961, and another in 1962, for the supply of raw water from Johor to Singapore.15

In 1963, Singapore merged with Malaya, Sabah and Sarawak to form the Federation of Malaysia, but after only two years, Singapore separated from Malaysia. As Singapore was heavily reliant on Malaysia for water, the 1961 and 1962 Water Agreements were guaranteed by the Singapore and Malaysia governments in the 1965 Separation Agreement, which was adopted by a constitutional amendment in Malaysia.16

A third agreement was signed in 1990, between PUB and Johor. Supplementary to the 1962 Water Agreement, this allowed PUB to construct the Linggiu Dam in Johor to enable the reliable extraction of water from the Johor River.17

In 1998, Singapore and Malaysia began a series of negotiations that included discussions on Malaysia’s supply of water to Singapore and the price at which Malaysia sold the water to Singapore. This was at a time when both countries were in an economic recession amid the Asian financial crisis.18 The talks ended without any progress.19 It was against this backdrop that PUB intensified its efforts to establish additional sources of water, namely, recycled water and desalinated water.

The 1961 Water Agreement expired in 2011, and Singapore continued to import water from Malaysia under the 1962 and 1990 agreements, which both expire in 2061.20

Third National Tap – NEWater
PUB first experimented with reclaiming water in the 1970s, but shelved the idea due to the high cost and unproven reliability of membrane technology. By the 1990s, technological advancements in water reclamation had significantly improved the performance of membrane technology and lowered the cost, prompting PUB to revisit the idea of recycling water, amid heightened water tensions between Singapore and Malaysia.21

After a study trip to the United States in 1998, PUB engineers assessed that it was feasible to reclaim water for potable purposes and set about building a full-scale demonstration plant in Bedok that could produce 2.2 million gallons per day (mgd). The plant started operations in 2000, and two years of intensive testing followed to ensure that reclaimed water was safe for drinking and posed no long-term health risks.22

NEWater was officially launched in 2003 with the opening of the first two NEWater plants in Bedok and Kranji.23 As of 2018, Singapore has five NEWater plants that can meet up to 40 percent of the nation's water demand. All used water in Singapore is first collected at water reclamation plants and treated to international standards before being channelled to the NEWater facilities for further purification.24

NEWater is expected to meet up to 55 percent of Singapore’s water needs by 2060.25 A sixth NEWater plant has been planned and is scheduled to commence operations by 2025.26

Fourth National Tap – desalinated water
Advancements in membrane technology allowed Singapore to develop its Fourth National Tap – desalinated water. In 2003, a private contractor was awarded the contract to design, build, own and operate the first desalination facility.27 Located in Tuas, the plant commenced operations in 2005 and has a production capacity of 30 mgd.28

A second privately operated desalination plant was opened in 2013.29 The third plant, owned and operated by PUB, opened in June 2018.30 Together, the three desalination plants can meet up to 30 percent of Singapore’s water demand. Two more desalination plants will be completed by 2020, with plans for desalinated water to meet up to 30 percent of the country’s water needs by 2060.31 The fourth plant, which is being built in Marina East, will be Singapore’s first large-scale dual-mode desalination plant, capable of treating both freshwater and seawater. Water will be drawn from either the nearby Marina Reservoir or the sea depending on prevailing weather conditions.32

Centre for Liveable Cities

1. Lim Swee Say, “Environment at SingSpring’s Desalination Plant Ground Breaking Ceremony,” speech, 16 January 2004, transcript, Ministry of the Environment (From National Archives of Singapore document no. MSE_20040116001)
2. “Four National Taps,” PUB, accessed 8 April 2019.
3. Tan Yong Soon, Lee Tung Jean and Karen Tan, Clean, Green and Blue: Singapore’s Journey Towards Environmental and Water Sustainability (Singapore: ISEAS Publishing, 2009), 127–29. (Call no. RSING 363.70095957 TAN)
4. “NeWater,” PUB, accessed 8 April 2019.
5. Jalelah Abu Baker, “When It Didn’t Rain, You Just Queued Up,” AsiaOne, 5 March 2014. (From Factiva via NLB’s eResources website)
6. PUB, Our Water: The Flow of Progress: Annual Report 2014/2015 (Singapore: PUB, 2015); “Singapore Water Story,” PUB, accessed 20 August 2018.
7. Public Utilities Board, Singapore, Our Water, Our Future (Singapore: Public Utilities Board, 2016), 11. (Call no. RSING 333.910095957 OUR)
8. Tan, Lee and Tan, Clean, Green and Blue, 127–29.
9. Tan, Lee and Tan, Clean, Green and Blue, 127–30; PUB, Annual Report 2014/2015, 6.
10. Tan Yong Soon, Lee Tung Jean and Karen Tan, “Cleaning the Land and Rivers,” in 50 Years of Environment: Singapore's Journey Towards Environmental Sustainability, ed., Tan Yong Soon (Singapore: World Scientific, 2016), 27–32. (Call no. RSING 333.72095957 FIF)
11. PUB, “Singapore Water Story.”
12. Ng How Yong, “Making Sure Singapore’s Taps Don’t Run Dry,” Today, 1 September 2015, 28. (From NewspaperSG)
13. Cecilia Tortajada, Yugal Joshi and Asit K. Biswas, The Singapore Water Story: Sustainable Development in an Urban City-State (New York: Routledge, 2013), 9–10. (Call no. RSING 363.61095957 TOR)
14. Parliament of Singapore, “Annex B: The Tebrau and Scudai Rivers Water Agreement between the Johore State Government and the City Council of Singapore Signed on 1 September 1961, vol. 75 of Parliamentary Debates: Official Report, 25 January 2003, cols. 2605–608. (Call no. RSING 328.5957 SIN)
15. Tan, Lee and Tan, Clean, Green and Blue, 139.
16. Edmund Lim, “Secret Documents Reveal Extent of Negotiations for Separation,” Straits Times, 22 December 2015, 20 (From NewspaperSG); Tortajada, Joshi and Biswas, The Singapore Water Story, 36–37.
17. Tan, Lee and Tan, Clean, Green and Blue, 139–40.
18. Ministry of Information, Communications and the Arts, Singapore, Water Talks? If Only It Could (Singapore: Ministry of Information, Communications and the Arts, 2003), 3. (Call no. RSING 327.59570595 WAT)
19. Ministry of Information, Communications and the Arts, Singapore, Water Talks?, 74–80.
20. M. Ghangaa, “Singapore's Water Supply: Where Does It Come from?” Straits Times, 5 August 2015. (From Factiva via NLB’s eResources website); Tan, Lee and Tan, Clean, Green and Blue, 140.
21. Tan, Lee and Tan, Clean, Green and Blue, 141–42.
22. Tan, Lee and Tan, Clean, Green and Blue, 142–44.
23. Public Utilities Board, Singapore, Our Water, Our Future, 9.
24. PUB, “NeWater.”
25. PUB, “NeWater.”
26. “Water Price Revisions 2017,” PUB, accessed 12 June 2019.
27. “State of The Environment 2005 Report,” “Milestones,” Hyflux, accessed 20 August 2019.
28. “Desalinated Water,” PUB, 20 August 2018; Harry Seah, “WaterTechOnline Interviews Harry Seah,” accessed 20 August 2018.
29. Woo Sian Boon, “New Desalination Plant Brings S’pore Closer to Self-Sufficiency,” Today, 19 September 2013, 1. (From NewspaperSG)
30. Jose Hong, “Singapore Opens Third Desalination Plant in Tuas,” Straits Times, 28 June 2018.  (From Factiva via NLB’s eResources website)
31. PUB, “Desalinated Water.”
32. PUB,Keppel Infrastructure and PUB Break Ground for Singapore’s First Dual-Mode Desalination Plant,” press release, 29 June 2017.

Further resources
Centre for Liveable Cities, Singapore and Public Utilities Board, Singapore, Water: From scarce Resource to National Asset (Singapore: Cengage Learning Asia, 2012). (Call no. RSING 333.91095957 WAT)

Tan Gee Paw, “Four National Taps: Singapore’s Water Resilience Story,” Urban Solutions, no. 7 (2015).

The information in this article is valid as at June 2019 and correct as far as we are able to ascertain from our sources. It is not intended to be an exhaustive or complete history of the subject. Please contact the Library for further reading materials on the topic.

Water-supply--Government policy--Singapore
Domestic policy (Water Resource Management)
Water resources development--Singapore