SE postcode district map, City of London

Where the SE districts sit

1 district is plotted without a label where labels would overlap; every one is in the table below.

Where SE sits

The whole area sits inside Greater London, which is unusual at this size.

Water supply across SE

All 29 SE districts are supplied by Thames Water, which is notable at this size: an area with this many districts usually crosses at least one supply boundary, and this one does not.

Thames Water has a hosepipe ban in force from 23 July 2026, covering the whole of SE.

The shape of the SE area

SE1 is the largest district with 2,008 postcodes around City of London, and SE24 the smallest with 295. The area divides into 128 postcode sectors.

Several districts share a settlement, which is a common source of confusion when a form rejects an address: SE1, SE3, SE4, SE6, SE7, SE8, SE10, SE12, SE13, SE14, SE15, SE16, SE18 and SE1P all point at City of London, SE5, SE11, SE17, SE19, SE20, SE21, SE22, SE23, SE24, SE26 and SE27 all point at City of Westminster and SE2 and SE28 all point at Dartford.

What borders SE

SE sits next to BR (Swanley) to the south east, EC (City of London) to the north west, WC (London) to the north west, E (City of London) to the north and SW (City of Westminster) to the west.

Its neighbours run in 4 different directions, so SE is landlocked by other postcode areas on most sides.

SE districts, settlements and water supply

Principal settlement is the town or city each district sits in or nearest to, derived from OS Open Names. It is not the Royal Mail post town, which is licensed data and not published openly. Status is resolved live from each company’s own notice.

Water hardness in SE

No water company covering SE publishes hardness figures as open data. The gap is named per district below so you know who to ask.

Hardness is published per census area, not per postcode, so these figures characterise a district rather than measuring one address. They are a scale and taste matter, not a safety one. Hardness data version wessex-water@2022-2025+yorkshire-water@2026.

Download the SE data

No signup, no email wall. GeoJSON carries the district points, the supplier and the live status, so it can be dropped straight into a map.

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District positions are averaged postcode centroids from OS Code-Point Open. They show roughly where a district sits, not where its boundary runs, and are not legal boundaries.

Frequently asked questions