Flood risk in SE21 (Southwark)
Of the 298 postcodes in SE21 – covering Southwark and Lambeth – none has its centre in Flood Zone 2 or 3 on the Environment Agency’s Flood Map for Planning. River and sea flood risk across the district is low.
Flood zones only cover rivers and the sea, and ignore flood defences. Surface water from heavy rain can affect any street, including in Zone 1.
Flood zones by postcode sector
Each sector is the first part of the postcode plus the first digit after the space.
| Sector | Postcodes | Zone 3 | Zone 2 | Breakdown |
|---|---|---|---|---|
| SE21 7 | 92 | 0% | 0% | |
| SE21 8 | 191 | 0% | 0% | |
| SE21 9 | 15 | 0% | 0% |
Main rivers in Southwark
River Thames – Tidal along Bankside, Bermondsey and Rotherhithe
River Effra – A buried river, now a sewer, under Dulwich
River Peck – A buried river, now a sewer, under Peckham
More on the area in our Southwark flood risk guide.
How these figures are worked out
We took the centre point of every live postcode in SE21 from OS Code-Point Open and tested it against the Environment Agency’s Flood Map for Planning, as published in the flood-risk-zone dataset (version of 5 November 2026). A postcode counts once, whether it has one home or forty, and a postcode whose centre is just outside a zone still counts as Zone 1. Updated November 2026.
For one address, the free postcode check looks at the zones around the postcode, and the full report adds surface water, reservoirs, recorded floods and defences.
