The sanitation system in Singapore

Singapore Infopedia


Singapore is served by a modern sanitation system in which all used water is collected through a network of sewers and channelled to water reclamation plants. But this was not always so.

In the 1800s, the sewage collection and disposal system in Singapore relied on the use of night soil buckets. In the 1900s, a network of sewers, pumping stations and treatment plants was developed and enhanced. Consequently, night soil disposal stations were phased out by 1987.

Improvements continued to be made in the wastewater treatment system so that by 1997, all of Singapore had access to modern sanitation.1 One of the key enhancements implemented is the Deep Tunnel Sewerage System (DTSS), which was conceptualised in the mid-1990s as a more sustainable solution to collect and treat used water before discharging it into the sea or channelling it to NEWater factories for further purification.2

Pre-independence Singapore
Before the introduction of sewers in Singapore, municipality residents depended on workers known as coolies to remove their human waste or “night soil”. The Chinese syndicates controlled these operations, where waste would be collected from houses in buckets and transported to market gardens and plantations for use as fertiliser.3

The removal of night soil remained an unregulated, private business until the late 1800s, when the municipal government sought to address the problems caused by the existing system, one of which was the use of wooden buckets to transport the night soil. The wooden buckets could not be covered properly and were extremely foul-smelling. The initial solution was to supply coolies with galvanised iron buckets, but the take-up rate was low. In 1889, a by-law was passed restricting the operating hours of night soil coolies who persisted in using wooden buckets. When this also proved ineffective, the use of wooden buckets was completely banned in 1891.4

The use of pit latrines with unpaved floors in houses also posed significant health risks due to the seepage of waste into the ground. To address this issue, such cesspits were abolished in the 1890s and house owners had to use pails or glazed earthenware jars placed on impermeable floors instead.At the same time, the Municipal Board built more public pail latrines in an attempt to get people to stop discharging their waste into drains. An 1897 survey showed that these public latrines were quite popular. However, the infrequent removal of night soil from these facilities meant that they eventually became a danger to public health and emitted a stench as well.6


In 1909, the municipal commissioners engaged a sanitary engineer, G. Midgeley Taylor of British firm Taylor, Sons & Santo Crimp, to make recommendations on sewage disposal in Singapore. Taylor proposed a water-borne sanitation system comprising a network of underground sewers to channel sewage to a pumping station, where it would then be sent to purification works for treatment before being discharged into the sea.

As Taylor’s proposed system was considered too ambitious, the municipal engineer, Robert Peirce,7 designed a modified scheme that could be developed in sections. The modified plan was adopted in 1911 and implemented gradually over the following decades. Focusing on the built-up part of the town, it consisted of a network of sewers, three pumping stations, and a central treatment and disposal works at Alexandra Road, from which treated effluent would be discharged into the Singapore River.8

As the new sewerage system only covered a small section of the municipality, it was also decided that the existing system of night soil collection and disposal had to be improved with greater government intervention. A municipally administered scheme of compulsory night soil collection was thus introduced in 1913 to replace the private services operated by the Chinese syndicates. However, implementation was slow, and by 1923, the municipal scheme had covered only about 15 percent of the total number of houses within municipal limits.9

As Singapore’s population grew, so did its sewage disposal needs. Although the Alexandra Sewage Disposal Works was expanded and upgraded, it was still unable to cope with the increasing load from both the sewerage network and night soil collection system. More pumping stations, a new sewage disposal works at Kim Chuan Road, and a sludge disposal works at Serangoon were added to the network by the 1940s.10 A new sewage treatment works at Ulu Pandan was subsequently completed in 1961 to replace the Alexandra Road facility.11

Development of a comprehensive sewerage network from the late 1960s
After Singapore achieved independence in 1965, the government decided to invest more in sewage management infrastructure as part of efforts to curb pollution of the nation’s precious water resources, improve the quality of life for the growing population and support the country’s continued economic growth. This led to the formulation of the Sewerage Master Plan in the late 1960s, which divided Singapore into six sewage catchment zones based on the contours of the island. Within each zone, pumping stations would channel sewage to a centralised treatment plant, where the sewage would be treated to international standards before being discharged into the sea.12

Under the Master Plan, additional sewage treatment plants in Bedok, Kranji, Seletar and Jurong were built between 1979 and 1985.13 By 1992, the network of sewer lines had grown from just 810 km in 1972 to 2,340 km, with the number of pumping stations increasing from 46 in 1972 to 136.14 This expansion of the sewerage network was carried out in tandem with other key developments in Singapore such as the relocation of squatters and street hawkers, the building of public housing estates and industrial parks, the renewal and redevelopment of the city centre, and the clean-up of the Singapore River.15

In 1984, with over 90 percent of the population served by a modern sanitation system, the government commenced its phasing out programme for the night soil bucket system. That year, it closed the night soil disposal station at Toh Tuck Road. The last night soil disposal station at Lorong Halus was closed in 1987, marking the end of this obsolete system.16 By 1997, all of Singapore had access to modern sanitation.17

Deep Tunnel Sewerage System (DTSS)
In the mid-1990s, the government conceptualised the Deep Tunnel Sewerage System (DTSS) as a more cost-effective and sustainable solution to meet Singapore’s needs in the long run.
18 Built in phases, the multi-billion dollar project is slated to eventually replace the existing system of sewage collection, treatment and disposal.19 Work on Phase 1 began in 2000 and was completed in 2008, after which the Kim Chuan, Seletar and Bedok water reclamation plants as well as the Serangoon Sludge Treatment Works were closed progressively.20 Construction of Phase 2 is scheduled for completion by 2025.21

When the DTSS is fully operational, used water will be conveyed through two deep tunnel sewers entirely by gravity to three centralised water reclamation plants (renamed from sewage treatment works in 2001).22 After undergoing treatment at the water reclamation plants, the water will be channelled to NEWater factories to produce NEWater, and any excess is discharged into the sea through the outfall pipes.23

Centre for Liveable Cities

1. 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), 183. (Call no. RSING 363.70095957 TAN)
2. Tan, Lee and Tan, Clean, Green and Blue, 187–88; Tan Gee Paw, Water (Singapore: Institute of Policy Studies; Straits Times Press Pte Ltd, 2016), 30. (Call no. RSING 363.61095957 TAN)
3. Brenda S.A. Yeoh, Contesting Space in Colonial Singapore: Power Relations and the Urban Built Environment (Singapore: Singapore University Press, 2003), 190–91. (Call no. RSING 307.76095957 YEO)
4. Yeoh, Contesting Space in Colonial Singapore, 195; “The Removal of Night Soil,” Straits Times Weekly Issue, 27 August 1890, 12. (From NewspaperSG)
5. Yeoh, Contesting Space in Colonial Singapore, 195.
6. Yeoh, Contesting Space in Colonial Singapore, 196.
7. “The Municipal Gallery,” Singapore Free Press and Mercantile Advertiser (Weekly), 24 July 1929, 8. (From NewspaperSG)
8. Yeoh, Contesting Space in Colonial Singapore, 201–02.
9. Yeoh, Contesting Space in Colonial Singapore, 202–04.
10. “New Sewerage Scheme Prepared for Alexandra Road Works,” Straits Times, 28 July 1934, 13; “$8,000,000 Sewerage Scheme Progresses,” Straits Times, 2 May 1940, 10; “Singapore Sewage Extensions Tested,” Straits Times, 15 April 1941, 11 (From NewspaperSG); Tan, Lee and Tan, Clean, Green and Blue, 181.
11. “Govt. Has Plan to Extend Sewerage System,” Singapore Free Press, 9 May 1961, 4; “50 Yrs. of Modern Sanitation in S’pore,” Straits Times, 20 December 1965, 12. (From NewspaperSG)
12. Tan, Lee and Tan, Clean, Green and Blue, 181–83.
13. PUB, Annual Report 2012/2013 (Singapore: PUB, 2013), 32.
14. Cecilia Tortajada, Yugal Joshi and Asit K. Biswas, The Singapore Water Story: Sustainable Development in an Urban City-State (New York: Routledge, 2013), 48. (Call no. RSING 363.61095957 TOR)
15. Jessica Cheam, Forging a Greener Tomorrow: Singapore's Environmental Journey from Slum to Eco-City (Singapore: Straits Times Press, 2012), 24–29. (Call no. RSING 363.70095957 CHE)
16. Tortajada, Joshi and Biswas, Singapore Water Story, 37–38; Tan, Water, 20.
17. Tan, Lee and Tan, Clean, Green and Blue, 183.
18. Tan, Lee and Tan, Clean, Green and Blue, 187–88; Tan, Water, 30.
19. Yeo Cheow Tong, “The Ground-Breaking Ceremony of the Ulu Pandan Sewerage Treatment Works Compact and Convered Extension,” speech, 25 March 1997, transcript, Ministry of Information, Communications and the Arts. (From National Archives of Singapore document no. 1997032501); Ministry of Information, Communications and the Arts, “Addendum to President's address in Parliament: Ministry of the Environment, press release, 30 May 1997. (From National Archives of Singapore document no. 1997053004)
20. Tan, Lee and Tan, Clean, Green and Blue, 136–37; Siau Ming En, “Construction Begins for S$6.5 Billion, 100km Superhighway for Used Water,” Today, 20 November 2017.
21. Navin Sregantan, “PUB Starts Second Phase of DTSS with S$2.3b of Work Contracted Out,” Business Times, 20 November 2017.
22. “About Deep Tunnel Sewerage System,” PUB, accessed 26 October 2019; Tan, Water, 29.
23. Ministry of the Environment and Water Resources, “Deep Tunnel Sewerage System (DTSS),” press release, 20 January 2001 (From National Archives of Singapore document no. MEWR20010120001); PUB, “Factsheet: About the Deep Tunnel Sewerage System (DTSS),” 20 November 2017 (From National Archives of Singapore); PUB, “About Deep Tunnel Sewerage System.”

Further resource
Centre for Liveable Cities, Singapore, Cleaning a Nation: Cultivating a Healthy Living Environment (Singapore: Centre for Liveable Cities, 2016)

The information in this article is valid as at February 2020  and correct as far as we are able to ascertain from our sources. It is not intended to be an exhaustive or complete history on the subject. Please contact the Library for further reading materials on the topic.

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