DL postcode district map, Darlington

Where the DL districts sit

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

Where DL sits

It falls across County Durham, North Yorkshire and Darlington.

Water supply across DL

All 18 DL districts are supplied by Northumbrian Water. That makes DL simple in a way many areas are not: one company, one set of rules, one status to check.

No hosepipe ban currently applies anywhere in DL.

The shape of the DL area

The districts are wildly uneven: DL1 holds 1,411 postcodes around Darlington and DL98 holds 6, a ratio of about 235 to one. They divide into 69 sectors.

The numbering is not continuous. DL runs up to 98 but has only 18 districts, so 80 numbers are unused:.

Several districts share a settlement, which is a common source of confusion when a form rejects an address: DL1, DL2, DL3 and DL98 all point at Darlington, DL9, DL10 and DL11 all point at Richmond and DL6 and DL7 all point at Northallerton.

What borders DL

DL sits next to DH (Durham) to the north, TS (Middlesbrough) to the east, SR (Sunderland) to the north east, HG (Harrogate) to the south and BD (Bradford) to the south.

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

DL 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 DL

Figures are in milligrams per litre as calcium carbonate, the unit UK water companies report in. 5 of 18 districts have a published figure.

Descriptions such as very soft, soft, moderately hard, hard, very hard are the water industry scale: very soft below 75, soft 75–125, moderately hard 125–250, hard 250–375, very hard above 375 mg/l. Your supplier may use a different scale for the same number.

Contains Yorkshire Water drinking water quality data, via Stream, licensed under CC BY 4.0. Edition 2026, published 1 January 2026. Yorkshire Water publishes this as mg/l without naming the species. We read it as calcium carbonate because the determinand is Hardness total and the dataset contains no calcium determinand. Evidence: determinand "Hardness total"; DWI code "HARD T"; no calcium determinand published in the dataset.

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 DL 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