PO postcode district map, Portsmouth

Where the PO districts sit

9 districts are plotted without a label where labels would overlap; every one is in the table below.

Where PO sits

It is administratively fragmented, reaching into Hampshire, West Sussex, Isle of Wight and City of Portsmouth and 0 other authorities.

Water supply across PO

All 35 PO districts are supplied by Portsmouth 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.

We are re-checking Portsmouth Water's status. It was last confirmed on 18 August 2026 as voluntary appeal, and until it is confirmed again this page does not assert a current position for it.

The shape of the PO area

The districts are wildly uneven: PO21 holds 1,352 postcodes around Bognor Regis and PO24 holds 1, a ratio of about 1352 to one. They divide into 129 sectors.

No single district dominates: the largest holds only about 6 per cent of the area's postcodes.

The numbering is not continuous. PO runs up to 41 but has only 35 districts, so 6 numbers are unused:.

Several districts share a settlement, which is a common source of confusion when a form rejects an address: PO1, PO2, PO3, PO4, PO5 and PO6 all point at Portsmouth, PO13, PO14, PO15 and PO16 all point at Fareham and PO39, PO40 and PO41 all point at Yarmouth.

PO24 is a non-geographic district: it carries no coordinates because it is used for PO boxes and large users rather than for streets. It appears in the table below but cannot be placed on the map.

What borders PO

PO sits next to SO (Southampton) to the north west, GU (Guildford) to the north east, BH (Bournemouth) to the west, SP (Salisbury) to the north west and BN (Brighton and Hove) to the east.

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

PO 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 PO

No water company covering PO 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 PO 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