Frequently Asked Questions

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.

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.

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.

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.

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

Click here to see a list of drainage improvement projects

PUB has been assisting and offering consultative advice to building owners whose premises have been affected from the recent flood incidents. PUB staff and contractors were on-site during flood events to help residents and premise owners pump out floodwater. PUB also provides technical advice on installing permanent flood protection measures, provide dedicated PUB contact persons and conduct regular briefings and provide updates on drainage works.

Click here for more information on protection measures.

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.

Inform PUB by calling our 24-hr Call Centre at 1800-284 6600. PUB will look into the situation and follow up on the case. PUB is also exploring with suppliers to fabricate a plus that can be placed on the floor trap to prevent floodwaters from coming out.

A tropical island surrounded by seas, Singapore receives abundant rainfall especially during the monsoon seasons. The average annual rainfall is about 2,400mm. Most times, our drains are able to cope with the rain that we receive. However, extremely heavy rainfall can sometimes exceed the capacity that the drains are designed for, especially in low-lying areas. That is when flash floods – small and localised floods that come and go relatively quickly – may occur.

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.

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, the crest gates at the dam will be activated to release excess storm water into the sea, when the sea tide is low. 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.

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.

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 a continual drainage improvement in flood prone areas.

Click here to find out more about flood management strategies.

There is no conclusive evidence that climate change caused the recent floods. However the Expert Panel on Drainage Design and Flood Protection Measures will be studying the effects of recent weather patterns.

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 integrating the cleaning functions of public areas, including the cleansing of drains, canals and waterways. This will be done in phases from April 1, 2012. The department is set up to better manage cleaning contracts, improve service standards and to improve responsiveness to public feedback. The DPC will ensure public areas are well-cleaned, and progressively integrate existing contracts by various agencies to achieve higher operational efficiency.

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 1800-2846600 or call DPC hotline at 1800-600-3333 or email dpc@nea.gov.sg to report.

Click here for more information on drainage maintenance.

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 1800-2846600 and tune in to the radio for latest news and updates.

As part of its monitoring system, PUB has installed 93 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 online or subscribe to the SMS alert service. Subscribers will receive progressive SMS alerts if the water level in the selected canal rises above 50%, 75%, 90% and 100% of the canal's depth. Separate SMS alerts will be sent to subscribers to inform them when the water level recedes gradually to below 50%.

Click here for more information on Water Level Sensors.
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.

The road raising project entails raising the stretch of Orchard Road, from Orange Grove Road to Cairnhill Road, to a level higher than that of the Canal. This helps prevent rainwater from overflowing onto the roads but instead contain it inside the canal to be conveyed towards Marina Reservoir. It will also help prevent future flash floods brought on by intense rainfall similar to that of 16 June 2010.

The Orchard Road raising project did not contribute to the flood incident on 5 June 2011. Water along Cuscaden Road is designed to flow towards Orchard Road. In fact, without the raising of Orchard Road, the situation would have been worse off given the higher intensity of rainfall. Flooding in the affected buildings was due to a combination of an excessive amount of rain which fell directly into the basements and the inability of the internal drainage pumps to cope. .

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.

NEA provides weather information and updates on their website (Weather@SG, rain animation, etc), through their Twitter account (@NEAsg) and their iPhone application (“myENV”). The public can now subscribe to heavy rain warning SMS alerts as well.

Click here to visit their website here for more details.

Click here to subscribe to the heavy rain warning SMS alerts.

PUB has completed the raising of Orchard Road (from Orange Grove Road to Cairnhill Road). It has also commissioned a study on the feasibility of building a detention pond and a diversion canal. The study commenced in August 2011 and will complete in the second half of 2012.

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). PUB has revised the Code of Practice on Surface Water Drainage. The changes include increasing minimum reclamation, as well as platform and crest, levels, and providing for high storm requirements for the drainage system. The revised version will take effect on 1 December 2011.

Safety railings are installed next to major canals and drains. Since May 2011, PUB has inspected and installed additional railings in areas where flash floods have occurred to ascertain if more railings are required. PUB has since installed about 6.5km of additional railings at 65 locations across the island.