Frequently Asked Questions


Click on the questions below to view their answers.

1. What is a flash flood?

A flash flood is flooding that is localised and subsides within a short period of time, usually within half an hour to an hour.

Click here to find out more about floods in Singapore.

2. Where are the flood-prone areas in Singapore?

Flood prone areas are those areas which are low-lying, with a history of flooding. Some of the flood-prone areas include Bukit Timah Road, Stevens Road, Arab Street and Rochor Canal.

Click here to find out more about our flood prone areas.

3. How does the water level sensor system work?

Water level sensors provide data on water levels in the drains and canals. This data sent to PUB staff, helps enhance forecasting capabilities and response time.

The public can also subscribe to SMS alerts of data from a location of their choice.

Click here for more information on water level sensors.
Click here for more information on subscribing to SMS alerts.

4. What should I do if I am caught in a flood/flash flood?

Pedestrians should be alert, move immediately to higher ground and stay put till the flood subsides. Be aware of your surroundings, especially if there are open drains.

Motorists should avoid driving into flooded areas if possible. If floodwaters rise around the vehicle, abandon vehicle and move to higher ground.

If you are indoors, protect your belongings by storing them on higher surfaces. Do not touch electrical equipment or switches if you are wet or standing in water.

Click here for more information on safety advisory.

5. What is PUB doing to address flood prone areas?

PUB conducts drainage improvement works as part of its long-term flood alleviation measures, and will continue to reduce the flood prone areas in Singapore.

Click here to see a list of drainage improvement projects

6. What is PUB doing to help those who are affected by the floods?

During flood events, PUB will respond to public requests for assistance to pump out floodwater. PUB also provides technical advice to residents and building owners on installing permanent flood protection measures and conducts regular briefings on completed and upcoming drainage works. Residents can also contact appointed PUB staff should they require any assistance or information.

Click here for more information on protection measures.

7. Can PUB install drainage pumps to prevent flooding in the low-lying areas?

It might not be feasible to install drainage pumps in many of the low-lying areas as land has to be set aside to build a pumping station but is hard to obtain in land-scarce Singapore.

8. What should I do when I see rising waters from the sanitary floor trap in my house during flooding?

Inform PUB by calling our 24-hr Call Centre at 1800-CALL-PUB (1800-2255 782). House owners can also consider installing a one-way valve at the last inspection chamber which will close to stop the accidental backflow of used water from the public sewer into the sanitary drainage system and hence prevent the overflowing at the floor trap.

9. Why do we still experience floods in Singapore?

Flash floods can occur due to a combination of factors such as:

- Peak runoff exceeding what the drain is designed to handle
 When the intensity of the storm is higher than what the drainage system is designed to handle, the large amount of runoff within a short period can overwhelm the drains and overflow to adjacent areas.
- Localised topographic characteristics
 Localised depressions on the roads and on the ground are naturally prone to water accumulation. In low-lying areas, options to reduce flooding are sometimes limited because the deepening of drains, especially those leading to the sea, would need to tie in with downstream levels.
- Clogged drainage systems
 Drains can get choked with leaves, litter and other debris that get washed into them during storms.

10. Can we solve the flood problem by widening and deepening drains and canals?

While flooding cannot be completely prevented, it can be alleviated with continual drainage improvement. Widening and deepening of drains and canals, and road raising are some ways of improving drainage.

In low-lying areas, however, drainage improvement projects are effective only if the surrounding ground level is also raised. Such projects will be carried out when the area is redeveloped. For existing older roads which are relatively low-lying and flood-prone, the road levels would be raised either in conjunction with drainage upgrading works or LTA’s road upgrading works as part of PUB’s plan to reduce flood-prone areas wherever possible.

11. How does Marina Barrage help in flood alleviation?

The Marina Barrage is a dam built across the Marina Channel to keep seawater out. It is part of a comprehensive flood control scheme to alleviate flooding in the low-lying areas in the city such as Chinatown, Boat Quay, Jalan Besar and Geylang. During heavy rain and low sea tide, the crest gates at the dam will be activated to release excess storm water into the sea. When the sea tide is high, giant pumps that are capable of pumping an Olympic-size swimming pool per minute, will drain excess storm water into the sea.

Click here to find out more about the Marina Barrage.

12. Are the recent floods due to the increased urbanization in Singapore?

Prior to any new land development or before construction begins in any area, PUB works together with agencies such as URA, HDB, LTA and JTC to map out necessary drainage measures.

13. What is PUB doing to alleviate floods?

PUB has a Flood Management Strategy to manage flood risks in Singapore. These include providing adequate drainage ahead of new developments; implementing flood protection measures; and continual drainage improvement in flood prone areas.

Click here to find out more about flood management strategies.

14. Is climate change a contributing factor to the recent floods?

In 2011, the Expert Panel on Drainage Design and Flood Protection Measures conducted a six-month review on flood protection and risk management measures that will be implemented in Singapore over the next decade. The experts noted that, based on the rainfall intensity records over the past 30 years, there is strong evidence of a trend towards higher rainfall intensities and frequency of intense rains. These up-trends are consistent with the Inter-governmental Panel on Climate Change 4th Assessment Report (IPCC AR4) and could add further strain on Singapore’s existing drainage infrastructure. PUB has put in place a multi-pronged plan that covers the entire spectrum of drainage and flood management. This includes implementing higher drainage design standards and holistic solutions, building new capabilities and working with stakeholders to improve preparedness. Through these efforts, we seek to minimise and mitigate the impact of flash floods in Singapore.

Click here to find out more about the key conclusions and recommendations of the Expert Panel.

15. Did poor maintenance contribute to floods?

To keep our drains free-flowing and able to perform to their designated capacities, PUB adopts a multi-barrier approach to trapping litter and litter collection as part of its litter management. Contractors are deployed island-wide to carry out physical cleansing, maintenance and minor structural repairs of drains and canals.

A new Department of Public Cleanliness (DPC) has been set up within the National Environment Agency, aimed at improving operational efficiency by integrating the cleaning functions of public areas (including the cleansing of drains, canals and waterways) by various agencies. This will be done in phases from April 1, 2012. In the long run, this will allow the DPC to better manage cleaning contracts, improve service standards and enhance responsiveness to public feedback. Choked drains, canals and dirty waterways will limit drainage capacity and prevent fast and effective drainage during heavy rain. Therefore everyone can do their part in keeping our waterways clean and litter free. If you see any choked drains or pollution in the waterways or reservoirs, you can call the PUB 24-hour Call Centre at 1800-CALL-PUB (1800-2255 782) or call DPC hotline at 1800-600-3333 or email to report. .

Click here for more information on drainage maintenance.

16. Can PUB inform the public of floods or potential floods?

The public can access PUB’s Facebook and Twitter accounts for the latest update on flash floods. They can also call the PUB 24-hour Call Centre at 1800-CALL-PUB (1800-2255 782) and tune in to the radio for the latest news.

As part of its monitoring system, PUB has installed 201 sensors in key canals and drains to track the water levels. The public is able to access information on the water levels in the canals either through PUB’s dedicated flash flood management website, an SMS alert service or PUB’s free mobile app “MyWaters”.

Click here for more information on Water Level Sensors and CCTV images.
Click here for more information on subscribing to SMS alerts.
Click here to go to PUB’s official Facebook Page.
Click here to go to PUB’s official Twitter page.

17. Why are there floods after the completion of the Marina Barrage?

The recent flooding incidents in Orchard Road (June 2010) and Cuscaden/Tomlinson Roads (June 2011) were due to the exceptional storms.

The Marina Barrage is part of a comprehensive flood control scheme to alleviate flooding in the low-lying areas in the city such as Chinatown, Boat Quay, Jalan Besar and Geylang. By removing tidal influence, the five rivers (Stamford Canal, Rochor Canal, Kallang River, Singapore River and Geylang River) are safe from back-flow of water as the water level within the Marina Reservoir can be kept constant or lowered when there is impeding storms.

By keeping seawater out, Marina Barrage acts as a tidal barrier to reduce flash floods in low-lying areas in the city. Its nine crest gates will be lowered if there is excess water in the basin. In the event that heavy rains coincide with high tides, seven drainage pumps will be activated to remove excess storm water in the basin.

18. How can I get weather information?

You can obtain the latest weather information via NEA weather forecast hotline at 6542 7788,, radio broadcasts and NEA’s myENV free mobile app.
The public can also subscribe to heavy rain warning SMS alerts. To subscribe, please click here.

19. Is PUB providing further flood protection for the Orchard Road area?

PUB has completed the raising of Orchard Road (from Orange Grove Road to Cairnhill Road) in 2011. It has also announced plans to increase the flood protection for the Stamford Canal catchment (which includes the Orchard Road area) by constructing a detention tank and diversion canal.

Click here for more information on enhancing flood protection for the Stamford Canal catchment.

20. What additional flood protection measures is PUB adopting to deal with the more intense storms?

To provide additional flood protection measures, PUB has in place a Code of Practice on Surface Water Drainage that stipulates drainage requirements. This includes minimum platform and crest levels for buildings and entrances to underground facilities (e.g. basement carparks, underground MRT stations, etc). The latest revision in December 2011 entailed raising the stipulated minimum height of platform, land reclamation and crest levels for new developments to provide better flood protection for buildings. The design parameters for new drains were also enhanced to cater to more intense rain storms.

Last updated on 17 Nov 2015