Surface water flooding
What is surface water flooding?
Surface water flooding is the main risk to London, appearing on London's Risk Register. Surface water (also known as flash flooding) occurs when heavy rainfall exceeds the ground’s capacity to absorb it or the sewer network’s capacity to drain it. It can lead to water flowing over the ground and pooling in low-lying areas. It is typically caused by short intense rainfall.
After heavy rain, it is expected to see some water in the road or on open land. This is not necessarily surface water flooding but is water ponding.
Most roads have highway gullies which will capture this water and drain it into the Thames Water sewer. The clearing of highways gullies is the responsibility of our Highways team.
If any of the following is present, then surface water flooding may be taking place:
- Water prevents access to a property, area of land or makes a highway impassable
- Water is still present after several hours and you believe the issue is being caused by a blocked or damaged roadside gully
There are gullies or drainage systems present in private estates or roads. These are the responsibility of the landowner or private management company, usually shared ownership between residents. Significant structures and their owners where the information is provided by the third party may be identified in the Flood Asset Register.
Report a surface water flooding incident to us
Report a blocked highways gully
Page last updated: 06 June 2023
