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The Early Years

The earliest drainage network in Singapore began as a public health measure. In the early 1900s, malaria was rampant as the malaria vector – the Anopheles mosquito – thrived in warm weather and bred easily in pools of stragnant water. To combat this, an anti-malarial drainage system was introduced in 1914 to convey seepage water and prevent formation of stagnant pools. The network compromised naturally-formed earth streams, subsoil pipes and concrete drains. With the growth and urbanisation of Singapore, the anti-malaria drains also served the purpose of flood alleviation.

In 1951, a Joint Committee on Flood Alleviation was formed. A number of flood alleviation projects were carried out in 1950s and 1960s, mainly in flood-prone areas such as Queenstown, Geylang, Bedok, Potong Pasir, Whampoa, Jurong, Tampines and Seletar. It was important to alleviate flooding in these areas, as they were densely built-up and flooding would affect a large number of residents. To improve their capacities to convey flood water to the sea, teh drains serving these areas were widened, deepened and concrete-lined.

At the same time, a tidal-gate system was also designed for the Central Business District and other areas in central Singapore tha were below the high tide level and faced frequent flooding during high tides.

Making Progress

In the mid-1970s, the Drainage Department from the Ministry of Environment worked with the Urban Redevelopment Authority, Housing Development Board and other agencies to draw up a comprehensive drainage masterplan. Taking into consideration the drainage requirements based on current and projected land uses, the masterplan guided the provisions of drainage systems and set aside drainage reserves for future requirements. The plan also targeted known flood-prone areas flood alleviation projects were laid out.

Some of these achievements are illustrated below:

Singapore River


The Singapore River is an important waterway and the main corridor for business activities for many decades. The river became heavily polluted from extensive business activities in and around the river until it was transformed in 1987 after a massive 10-year clean-up involving many agencies.

Today, the Singapore River is a popular recreational and cultural venue. It is one of the five rivers that flows into the Marina Reservoir.

Geylang River

Geylang River

The Geylang River is the main drainage artery serving the Geylang area and Tanjong Katong drainage catchment. PUB spent some S$41 million to alleviate the flood situation in the area. Today, it is a clean and beautiful waterway that is both functional and aesthetically-pleasing.

Sungei Api Api

Sungei Api Api

Sungei Api Api is one of the major watercourses serving parts of Pasir Ris and Tampines New Towns.

PUB adopted an integrated design approach when redesigning the river to create a natural-looking infrastructure in an urban jungle. The river was deepened to 2 metres below low tide to ensure permanent flow of water. Specially selected plants and mangroves also lined the river banks to enhance the natural environment.

While Sungei Api Api offers spectacular views to the residents, it continues to provide the functional need for drainage. It has become the first in a series of river improvement projects involving waterscaping and landscaping of Singapore waterways.


Since 1973, more than S$2 billion has been spent on the construction of new drains and canals in Singapore. Through concerted effort and careful land development planning, PUB has reduced Singapore’s flood prone areas from 3,200 ha in the 1970s to the current 56 ha. Nevertheless, flash floods and ponding still occur in small parts of Singapore. PUB is now targeting its flood-prone projects in these areas.

  • Read more about our efforts in managing Singapore's drainage system and flash floods.

Singapore also uses the network of drains, canals, rivers, stormwater collection ponds and reservoirs to collect rainwater before it is treated for drinking water supply. This makes Singapore one of the few countries in the world to harvest urban storm-water on a large-scale for its water supply.

In 2007, PUB also rolled out the Active, Beautiful, Clean Waters (ABC Waters) Programme which is transforming Singapore’s drains, canals and reservoirs into beautiful and clean streams, rivers and lakes. With more than 100 projects in the next 10-15 years, the masterplan will transform the nation into a City of Gardens and Water. By 2012, over 20 projects will be realised under Phase One.

  • Click here to know more about the ABC Waters programme.
Last updated on 23 Sep 2011