SE20: 23 m clear of the highest tide in the London Bridge ledgers

The lowest postcode in SE20, SE20 7NP, stands 23 m above the highest tide in the London Bridge ledgers (5.41 m, 1 February 1953). The highest, SE20 8AX, stands 65 m above it.
- Ground at eight in ten of its postcodes: between 33 m and 58 m, measured from Ordnance Datum; the middle one stands at 42 m.
- None lies in the Environment Agency's Flood Zone 3 from the sea.
- In Bromley.