DT postcode district map, Dorchester
Supplier statuses last checked .
The DT postcode area covers 11 districts and 7,945 live postcodes, from DT1 to DT11. It is centred on Dorchester and also covers Blandford Forum, Weymouth, Bridport, Sherborne and Chickerell.
Districts here average 722 postcodes.
Where the DT districts sit
Where DT sits
It falls across Dorset, Somerset and Devon.
Water supply across DT
DT is split between Wessex Water, which supplies 10 districts and South West Water, which supplies 1 district (DT7). Which one bills you decides which rules apply to you,.
Wessex Water has a hosepipe ban in force from 18 August 2026, covering 10 of the 11 DT districts.
South West Water has a hosepipe ban in force from 8 August 2026, covering 1 of the 11 DT districts (DT7).
The shape of the DT area
DT2 is the largest district with 1,140 postcodes around Dorchester, and DT8 the smallest with 234. The area divides into 39 postcode sectors.
District by district: DT1 serves Dorchester, DT2 serves Dorchester, DT3 serves Chickerell, DT4 serves Weymouth, DT5 serves Fortuneswell, DT6 serves Bridport, DT7 serves Lyme Regis, DT8 serves Beaminster, DT9 serves Sherborne, DT10 serves Sturminster Newton and DT11 serves Blandford Forum.
Several districts share a settlement, which is a common source of confusion when a form rejects an address: DT1 and DT2 all point at Dorchester.
What borders DT
DT sits next to BH (Bournemouth) to the east, BA (Bath) to the north, TA (Taunton) to the north west, SP (Salisbury) to the north east and BS (Bristol) to the north.
Its neighbours run in 4 different directions, so DT is landlocked by other postcode areas on most sides.
DT districts, settlements and water supply
| District | Principal settlement | Water company | Hosepipe ban status |
|---|---|---|---|
| DT1 | Dorchester | Wessex Water / South West Water | Ban in force |
| DT2 | Dorchester | Wessex Water / South West Water | Ban in force |
| DT3 | Chickerell | Wessex Water / South West Water | Ban in force |
| DT4 | Weymouth | Wessex Water / South West Water | Ban in force |
| DT5 | Fortuneswell | Wessex Water / South West Water | Ban in force |
| DT6 | Bridport | Wessex Water / South West Water | Ban in force |
| DT7 | Lyme Regis | South West Water | Ban in force |
| DT8 | Beaminster | Wessex Water / South West Water | Ban in force |
| DT9 | Sherborne | Wessex Water / South West Water | Ban in force |
| DT10 | Sturminster Newton | Wessex Water / South West Water | Ban in force |
| DT11 | Blandford Forum | Wessex Water / South West 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 DT
Figures are in milligrams per litre as calcium carbonate, the unit UK water companies report in. 11 of 11 districts have a published figure.
| District | Hardness | As published | Supply zone | Published by |
|---|---|---|---|---|
| DT1 | 294.8 mg/l That is hard on the water industry scale. | 294.8 mg/l as CaCO₃ | E01020505, E01020518, E01020520, E01020523 +13 more | Wessex Water 2022-2025 edition |
| DT2 | 285.3 mg/l That is hard on the water industry scale. | 285.3 mg/l as CaCO₃ | E01020509, E01020510, E01020529, E01020534 +2 more | Wessex Water 2022-2025 edition |
| DT3 | 280.1 mg/l That is hard on the water industry scale. | 280.1 mg/l as CaCO₃ | E01020512, E01020551, E01020552, E01020557 +7 more | Wessex Water 2022-2025 edition |
| DT4 | 281.9 mg/l That is hard on the water industry scale. | 281.9 mg/l as CaCO₃ | E01020513, E01020514, E01020515, E01020516 +16 more | Wessex Water 2022-2025 edition |
| DT5 | 282.9 mg/l That is hard on the water industry scale. | 282.9 mg/l as CaCO₃ | E01020562, E01020563, E01020564, E01020565 +3 more | Wessex Water 2022-2025 edition |
| DT6 | 242.8–300 mg/l varies across this district | 271.7 mg/l as CaCO₃ | E01020498, E01020499, E01020500, E01020501 +7 more | Wessex Water 2022-2025 edition |
| DT7 | 285.9 mg/l That is hard on the water industry scale. | 285.9 mg/l as CaCO₃ | E01020511 | Wessex Water 2022-2025 edition |
| DT8 | 314.4 mg/l That is hard on the water industry scale. | 314.4 mg/l as CaCO₃ | E01020494, E01020495, E01020496, E01020506 +1 more | Wessex Water 2022-2025 edition |
| DT9 | 271.5–382.3 mg/l varies across this district | 356.5 mg/l as CaCO₃ | E01020508, E01020541, E01020542, E01020543 +7 more | Wessex Water 2022-2025 edition |
| DT10 | 283.8 mg/l That is hard on the water industry scale. | 283.8 mg/l as CaCO₃ | E01020433, E01020434, E01020441, E01020448 +4 more | Wessex Water 2022-2025 edition |
| DT11 | 295.5 mg/l That is hard on the water industry scale. | 295.5 mg/l as CaCO₃ | E01020430, E01020431, E01020432, E01020435 +11 more | Wessex Water 2022-2025 edition |
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 Wessex Water drinking water quality data, via Stream, licensed under CC BY 4.0. Edition 2022-2025, published 1 January 2025.
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 DT 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 DT area?
There are 11 DT postcode districts, running from DT1 to DT11, and they contain 7,945 live postcodes across 39 sectors.
What towns does the DT postcode area cover?
DT covers Dorchester, Blandford Forum, Weymouth, Bridport, Sherborne and Chickerell. The area takes its name from Dorchester, and each district is listed with its settlement in the table on this page.
Why do neighbours in DT have different hosepipe rules?
Because 2 different water companies supply DT: Wessex Water and South West Water. A hosepipe ban is declared by a company for its own customers, not by council or by postcode, so two houses on the same street with different suppliers can be under different rules on the same day. The supplier named on your water bill is the one whose rules apply to you.
Why do DT1 and DT2 both say Dorchester?
DT1 and DT2 all serve Dorchester, 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 DT postcode map?
Yes. This page offers the DT 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.
Which councils cover the DT postcode area?
DT reaches into Dorset, Somerset and Devon. A postcode area is not a council area: they were drawn for different purposes and a single district can sit across a council boundary, so your postcode does not tell you which authority you pay.
How many postcode sectors are in DT?
DT contains 39 postcode sectors across its 11 districts. A sector is the district plus the first digit of the second half of the postcode, and it is the level a delivery round is actually planned around.