Flood risk across London
Much of central and east London is tidal floodplain protected by the Thames Barrier, in operation since 1982, and hundreds of kilometres of river walls. Flood zones ignore those defences, so large parts of the city show as Flood Zone 3. Surface water is the bigger day-to-day risk: in July 2021 intense storms flooded homes, roads and Tube stations across the capital.
Flood zones only show river and sea flooding, and they ignore flood defences. Surface water and reservoir risk aren’t part of the zones – check them on the Environment Agency’s long-term flood risk service, or get the full report, which covers every source.
Rivers that shape local flood risk
Main rivers are managed by the Environment Agency. Smaller watercourses and drainage are the responsibility of the borough councils and landowners.
River Thames – Tidal from Teddington Lock to the estuary
River Lea – The Lee Valley, Stratford and Bow Creek
River Wandle – Croydon, Merton and Wandsworth
River Brent – Brent, Ealing and Brentford
River Ravensbourne – Bromley, Lewisham and Deptford Creek
River Roding – Redbridge and Barking
Who manages flood risk here
Each London borough (and the City of London Corporation) is the Lead Local Flood Authority for its area, responsible for surface water, groundwater and ordinary watercourses. The Environment Agency manages main rivers and the sea, and issues flood warnings. Your borough council also decides planning applications – and asks for a flood risk assessment in Flood Zones 2 and 3.
Getting a written answer for an address
The free check describes the area around your postcode. For a specific property, the full report checks your exact address against every flood dataset and gives you a dated PDF to share with your surveyor, conveyancer or insurer.
For planning decisions, your local council has the final say.
