SO21 Flood Risk
In postcode district SO21 (Winchester), 77 of 13,044 properties (0.6%) are in areas at high or medium risk of flooding from rivers and the sea — at least a 1 in 100 chance in any year — per Environment Agency data updated 6 July 2026; that is the 1,163rd highest count of 2,181 districts in England.
By bandProperties in SO21 by flood-risk band
| Risk band | Chance of flooding each year | All properties | Homes |
|---|---|---|---|
| High | 3.3% (1 in 30) or greater chance in any year | 50 | 26 |
| Medium | between 1% and 3.3% (1 in 100 to 1 in 30) chance in any year | 27 | 19 |
| Low | between 0.1% and 1% (1 in 1,000 to 1 in 100) chance in any year | 64 | 44 |
| Very low | less than 0.1% (1 in 1,000) chance in any year | 65 | 52 |
45 of the high- or medium-risk properties are homes and 13 are non-residential (shops, offices, farms, public buildings); the rest are unclassified. By share, SO21 ranks 1,192nd of 2,084 districts with at least 500 properties.
Postcode sectorsWhere in SO21 the risk sits
| Sector | Properties | High | Medium | Low | Very low | High + medium share |
|---|---|---|---|---|---|---|
| SO21 1 | 5,294 | 22 | 0 | 6 | 29 | 0.4% |
| SO21 2 | 3,714 | 16 | 2 | 32 | 36 | 0.5% |
| SO21 3 | 4,036 | 12 | 25 | 26 | 0 | 0.9% |
Recorded floodsPast floods mapped near SO21
The Environment Agency has mapped flood outlines on 9 dates near SO21 since 1995; the most recent started on 18 Feb 2014.
| Started | Place / name in the record | Source of flooding | Cause |
|---|---|---|---|
| 18 Feb 2014 | King Charles Pub, Kingsworthy 3 outlines | Other | Groundwater/high water table |
| 15 Feb 2014 | Village Hall, Sutton Scotney | Main river | Groundwater/high water table |
| 9 Feb 2014 | Headbourne Worthy, Winchester | Main river | Groundwater/high water table |
| 1 Jan 2001 | River Dever Micheldever | Ephemeral watercourse | Groundwater/high water table |
| 1 Dec 2000 – 1 Mar 2001 | River Dever Sutton Scotney 7 outlines | Ephemeral watercourse | Groundwater/high water table |
| 1 Nov 2000 – 1 Jan 2001 | Nunswalk St Headbourne Worthy 3 outlines | Ephemeral watercourse | Groundwater/high water table |
| 1 Jan 2000 | River Dever Wonston | Ephemeral watercourse | Groundwater/high water table |
| 12 Feb 1995 – 27 Mar 1995 | Nuns Walk Stream Harestock | Ephemeral watercourse | Groundwater/high water table |
| 1 Jan 1995 – 1 Apr 1995 | River Dever 16 outlines | Ephemeral watercourse | Groundwater/high water table |
What this page shows, and what it misses
The Environment Agency's count of properties in each postcode that sit in areas of land at very low, low, medium or high risk of flooding from rivers and the sea, allowing for flood defences and their condition, added up here by postcode district and local authority. Every property in England is counted once, so the share is of all properties in the area.
It misses: surface water (heavy rain), groundwater, sewer and reservoir flooding; Wales, Scotland and Northern Ireland; and anything about a single building. A band describes the land a property stands on, not its floor level or flood protection, so it is not a forecast for any one home. Past floods come from the EA's Recorded Flood Outlines and are placed in the postcode district whose centre is nearest (within 12 km), so a flood near a boundary can be listed under a neighbour. Older records are patchy, and a flood with no outline is not listed.
Local authorities in SO21
- Winchester — 12,638 properties, 67 at high or medium risk
- Test Valley — 406 properties, 10 at high or medium risk
Parishes in SO21: Allbrook, Ampfield, Barton Stacey, Bullington, Cheriton, Chilcomb, Colden Common, Compton and Shawford, Crawley, Headbourne Worthy, Hursley, Itchen Valley, Kings Worthy, Laverstoke, Littleton and Harestock, Longparish, Micheldever, Otterbourne, Owslebury, Popham, South Wonston, Sparsholt, Steventon, Tichborne, Twyford, Wonston.
If you live in SO21
- Check your own address on gov.uk; it also covers surface water.
- Sign up for free flood warnings by phone, text or email: gov.uk/get-flood-warnings.
- See what is in force now on flood warnings UK, and river levels. Floodline: 0345 988 1188.
- Never walk or drive through flood water: why shallow water kills.
Nearby districts
FAQQuestions people ask
Is SO21 at risk of flooding?
In postcode district SO21 (Winchester), 77 of 13,044 properties (0.6%) are in areas at high or medium risk of flooding from rivers and the sea — at least a 1 in 100 chance in any year — per Environment Agency data updated 6 July 2026; that is the 1,163rd highest count of 2,181 districts in England.
How many homes in SO21 are at high risk of flooding?
26 homes (residential properties) in SO21 are in areas at high risk (3.3% or greater chance each year) and 19 at medium risk, out of 9,201 homes, per Environment Agency data updated 6 July 2026. This counts rivers and the sea only, not surface water.
Has SO21 flooded before?
The Environment Agency has mapped flood outlines on 9 dates near SO21 since 1995; the most recent started on 18 Feb 2014.
How do I check the flood risk for my own address in SO21?
Use the government's long-term flood risk checker (check-long-term-flood-risk.service.gov.uk): it shows rivers and the sea, surface water, reservoirs and groundwater for one address. District figures here are totals and cannot tell you about a single home.
Flood risk counts: Environment Agency, Risk of Flooding from Rivers and Sea – Postcodes in Areas at Risk and Recorded Flood Outlines, used under the Open Government Licence v3.0. © Environment Agency copyright and/or database right 2025. All rights reserved. Some features of this information are based on digital spatial data from the Centre for Ecology & Hydrology, © NERC (CEH). © Crown Copyright and Database Rights 2025 OS AC0000807064. This product is produced in part from PAF® and Multiple Residence Data, the copyright in which is owned by Royal Mail Group Limited and/or Royal Mail Group plc. All rights reserved. Licence number AC0000807064.
Local authority of each postcode: Office for National Statistics postcode lookup (May 2026), licensed under the Open Government Licence v3.0. Contains OS data © Crown copyright and database right 2026. Contains Royal Mail data © Royal Mail copyright and database right 2026. District centres and place names: postcodes.io (ONS/OS open data). Totals, ranks and grouping are Global Incident Tracker's own calculations; the Environment Agency does not endorse them.