SW postcode district map, City of Westminster
Supplier statuses last checked .
The SW postcode area covers 28 districts and 20,109 live postcodes, from SW2 to SW1Y. It is centred on City of Westminster and also covers Ewell and London.
Districts here average 718 postcodes.
Where the SW districts sit
5 districts are plotted without a label where labels would overlap; every one is in the table below.
Where SW sits
The whole area sits inside Greater London, which is unusual at this size.
Water supply across SW
All 28 SW 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 SW.
The shape of the SW area
SW19 is the largest district with 1,659 postcodes around Ewell, and SW95 the smallest with 44. The area divides into 137 postcode sectors.
The numbering is not continuous. SW runs up to 95 but has only 28 districts, so 74 numbers are unused:.
Several districts share a settlement, which is a common source of confusion when a form rejects an address: SW2, SW3, SW4, SW5, SW6, SW7, SW8, SW9, SW10, SW11, SW12, SW13, SW14, SW15, SW16, SW17, SW18, SW95, SW1A, SW1E, SW1H, SW1P, SW1V, SW1W and SW1X all point at City of Westminster and SW19 and SW20 all point at Ewell.
What borders SW
SW sits next to W (London) to the north west, WC (London) to the north east, EC (City of London) to the north east, SM (Ewell) to the south and NW (London) to the north.
Its neighbours run in 4 different directions, so SW is landlocked by other postcode areas on most sides.
SW districts, settlements and water supply
| District | Principal settlement | Water company | Hosepipe ban status |
|---|---|---|---|
| SW2 | City of Westminster | Thames Water | Ban in force |
| SW3 | City of Westminster | Thames Water | Ban in force |
| SW4 | City of Westminster | Thames Water | Ban in force |
| SW5 | City of Westminster | Thames Water | Ban in force |
| SW6 | City of Westminster | Thames Water | Ban in force |
| SW7 | City of Westminster | Thames Water | Ban in force |
| SW8 | City of Westminster | Thames Water | Ban in force |
| SW9 | City of Westminster | Thames Water | Ban in force |
| SW10 | City of Westminster | Thames Water | Ban in force |
| SW11 | City of Westminster | Thames Water | Ban in force |
| SW12 | City of Westminster | Thames Water | Ban in force |
| SW13 | City of Westminster | Thames Water | Ban in force |
| SW14 | City of Westminster | Thames Water | Ban in force |
| SW15 | City of Westminster | Thames Water | Ban in force |
| SW16 | City of Westminster | Thames Water | Ban in force |
| SW17 | City of Westminster | Thames Water | Ban in force |
| SW18 | City of Westminster | Thames Water | Ban in force |
| SW19 | Ewell | Thames Water | Ban in force |
| SW20 | Ewell | Thames Water | Ban in force |
| SW95 | City of Westminster | Thames Water | Ban in force |
| SW1A | City of Westminster | Thames Water | Ban in force |
| SW1E | City of Westminster | Thames Water | Ban in force |
| SW1H | City of Westminster | Thames Water | Ban in force |
| SW1P | City of Westminster | Thames Water | Ban in force |
| SW1V | City of Westminster | Thames Water | Ban in force |
| SW1W | City of Westminster | Thames Water | Ban in force |
| SW1X | City of Westminster | Thames Water | Ban in force |
| SW1Y | London | Thames Water | Ban in force |
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 SW
No water company covering SW publishes hardness figures as open data. The gap is named per district below so you know who to ask.
| District | Hardness | As published | Supply zone | Published by |
|---|---|---|---|---|
| SW2 | Not published by Thames Water. Check with your supplier. | |||
| SW3 | Not published by Thames Water. Check with your supplier. | |||
| SW4 | Not published by Thames Water. Check with your supplier. | |||
| SW5 | Not published by Thames Water. Check with your supplier. | |||
| SW6 | Not published by Thames Water. Check with your supplier. | |||
| SW7 | Not published by Thames Water. Check with your supplier. | |||
| SW8 | Not published by Thames Water. Check with your supplier. | |||
| SW9 | Not published by Thames Water. Check with your supplier. | |||
| SW10 | Not published by Thames Water. Check with your supplier. | |||
| SW11 | Not published by Thames Water. Check with your supplier. | |||
| SW12 | Not published by Thames Water. Check with your supplier. | |||
| SW13 | Not published by Thames Water. Check with your supplier. | |||
| SW14 | Not published by Thames Water. Check with your supplier. | |||
| SW15 | Not published by Thames Water. Check with your supplier. | |||
| SW16 | Not published by Thames Water. Check with your supplier. | |||
| SW17 | Not published by Thames Water. Check with your supplier. | |||
| SW18 | Not published by Thames Water. Check with your supplier. | |||
| SW19 | Not published by Thames Water. Check with your supplier. | |||
| SW20 | Not published by Thames Water. Check with your supplier. | |||
| SW95 | Not published by Thames Water. Check with your supplier. | |||
| SW1A | Not published by Thames Water. Check with your supplier. | |||
| SW1E | Not published by Thames Water. Check with your supplier. | |||
| SW1H | Not published by Thames Water. Check with your supplier. | |||
| SW1P | Not published by Thames Water. Check with your supplier. | |||
| SW1V | Not published by Thames Water. Check with your supplier. | |||
| SW1W | Not published by Thames Water. Check with your supplier. | |||
| SW1X | Not published by Thames Water. Check with your supplier. | |||
| SW1Y | Not published by Thames Water. Check with your supplier. | |||
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 SW 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.
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
How many postcode districts are in the SW area?
There are 28 SW postcode districts, running from SW2 to SW1Y, and they contain 20,109 live postcodes across 137 sectors.
What towns does the SW postcode area cover?
SW covers City of Westminster, Ewell and London. The area takes its name from City of Westminster, and each district is listed with its settlement in the table on this page.
Which water company supplies SW postcodes?
Thames Water supplies all 28 SW districts. Supply boundaries follow the pipe network rather than postcode geography, so confirm against your water bill if you are near the edge of the area.
Why do SW2 and SW3 both say City of Westminster?
SW2, SW3, SW4, SW5, SW6, SW7, SW8, SW9, SW10, SW11, SW12, SW13, SW14, SW15, SW16, SW17, SW18, SW95, SW1A, SW1E, SW1H, SW1P, SW1V, SW1W and SW1X all serve City of Westminster, covering different parts of it. A single town routinely needs more than one postcode district once it passes a few thousand delivery points, so this is normal rather than an error in an address.
Can I download a free SW postcode map?
Yes. This page offers the SW districts as GeoJSON, CSV and SVG, free and with no signup or email address required. The GeoJSON carries each district's position, its water company and its current restriction status, so it can be dropped straight into a mapping tool.
Why is the SW area called City of Westminster when it covers Ewell?
SW takes its letters from City of Westminster, where the sorting office that served the area was based when the code was allocated. Ewell is the largest settlement in the area today, in SW19, but the area code follows the historic sorting geography rather than current population.
Why is there no SW94 postcode district?
SW94 is not in use. Postcode districts are allocated as sorting requirements change rather than numbered straight through, and a code that is retired or never brought into service is not reissued, so gaps in the sequence are normal.