Oral Reply to Parliamentary Question on Drainage Improvement

Questions:

Mr Desmond Choo: To ask the Minister for Sustainability and the Environment in light of the recent flash floods in Singapore caused by the monsoon surges in recent months (a) whether the Ministry will consider conducting additional in-depth reviews on the adequacy of our drainage systems to deal with such monsoon surges; and (b) whether the current investments by the Government to improve drainage infrastructure are sufficient.

Mr Saktiandi Supaat: To ask the Minister for Sustainability and the Environment in light of the monsoon surges in January 2025 (a) how many different areas reported flooding of (i) up to 0.5 metre (ii) between 0.5 and 1 metre and (iii) more than 1 metre above ground level; (b) out of these areas, how many have reported previous incidents of flooding in the past five years; and (c) what is the Ministry’s strategy to prevent and respond to flooding situations going forward.

Miss Rachel Ong: To ask the Minister for Sustainability and the Environment what are the plans are to improve drainage in areas that have shown to be prone to flooding during the recent monsoon surge.

Answer:

In January this year, Singapore and the region experienced two monsoon surges which brought about prolonged rain. The first monsoon surge lasted four days from 10 to 13 January and the second monsoon surge lasted three days from 17 to 19 January. During the first monsoon surge, a total of 255.2 mm of rainfall was recorded at Changi from 10 to 11 January, which is more than Singapore’s average monthly rainfall of 222.4 mm in January.   

2 Over the two monsoon surges in January 2025, there was one incident of flooding, which occurred at Jalan Seaview. Jalan Seaview is a low-lying area subject to tidal influence. Since the 1980s, a tidal gate has been in place in the outlet drain downstream of Jalan Seaview, to help mitigate tidal flood risks for this area. On 10 January, heavy rain coincided with high tide, and this led to the flooding at the side road bend of Jalan Seaview. The flooding on the road was about 0.3 metres and lasted close to three hours due to the high tide. The house next to this road experienced flooding within its car porch area. Based on PUB’s records, in the past five years, this is the only stretch of road along Jalan Seaview that has experienced flooding. 

3 While PUB had upgraded the roadside drains at Jalan Seaview in 2014 to increase their drainage capacity, some areas in the vicinity of Jalan Seaview are still susceptible to flooding, as the road levels are marginally above the high tide level. The longer-term plan is to reclaim and build Long Island which will protect the East Coast area, including Jalan Seaview, from rising sea levels and tidal floods. Agencies have initiated technical studies and are engaging the public and stakeholders to shape the plans for Long Island.

4 We encourage developments in low-lying areas, including at Jalan Seaview, to put in place their own flood protection measures, such as deploying flood protection devices. To help residents and businesses, PUB has been issuing flood protection devices, such as flood barriers and inflatable sand bags, as part of the annual monsoon preparation and providing guidance on how to deploy these devices properly and in a timely manner.  

5 Climate change will increase flood risks in Singapore due to more extreme and unpredictable rainfall. PUB adopts a multi-pronged approach to enhance Singapore’s flood resilience.

Upgrading drainage infrastructure

6 First, PUB continually upgrades our drainage infrastructure. The Government has made significant investments over the decades to upgrade drainage infrastructure, with about $2.5 billion spent since 2011. We have successfully reduced flood prone areas from approximately 3,200 hectares in the 1970s to less than 25 hectares today. PUB conducts regular reviews on the adequacy of the existing drainage system and considers the latest drainage design standards and climate change data. There are 19 ongoing drainage upgrading works, with six more projects slated to commence in 2025. We will spend about $150 million on these projects in FY2025. We are currently reviewing the drainage infrastructure plan for the next review cycle of FY2026-2030.

7 That said, it is neither practical nor prudent in land-scarce Singapore to keep building more drains or expanding our drainage infrastructure. Doing so would require significant land and financial resources, which would then not be available for other important uses. To put things into perspective, flooding in Singapore is localised and typically subsides within an hour. Instead, it is more effective to build up flood resilience at a systems level, where building owners and developers, as well as the wider community, all play their part alongside the Government.

Building shared responsibility

8 To this end, PUB works closely with building owners and developers on measures that have to be taken at the individual development level to strengthen flood resilience. PUB’s Code of Practice (or COP) on Surface Water Drainage provides requirements on minimum platform and crest levels for buildings, and flood protection measures that building owners and developers must implement to protect their premises. Amendments to the Sewerage and Drainage Act were passed in November 2024 to ensure that owners and developers continue to operate and maintain the flood protection measures in their premises properly after implementation. 

Building community resilience

9 PUB also proactively engages the community to better prepare for and respond to flood incidents. PUB works with NEA to forecast intense rainfall and issue early warning of potential floods to better prepare the public ahead of flood incidents. PUB launched its inaugural flood preparedness campaign “Get Flood-wise” in November 2024 and worked with partners, such as Grab and BlueSG, to share flood readiness tips with drivers and commuters.

10 Managing flood risks is a collective effort between the Government, businesses, and the public. I encourage everyone to play their part in enhancing Singapore’s flood resilience.