Hillingdon Flood Risk
In Hillingdon, 2,383 of 135,669 properties (1.8%) 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 ranks 93rd of 296 local authorities in England by number.
By bandProperties in Hillingdon 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 | 1,544 | 886 |
| Medium | between 1% and 3.3% (1 in 100 to 1 in 30) chance in any year | 839 | 696 |
| Low | between 0.1% and 1% (1 in 1,000 to 1 in 100) chance in any year | 3,752 | 3,204 |
| Very low | less than 0.1% (1 in 1,000) chance in any year | 533 | 476 |
1,582 of the high- or medium-risk properties are homes and 741 are non-residential. 210 postcodes in Hillingdon have at least one property at high or medium risk.
Postcode districtsFlood risk across Hillingdon
Counts are for the part of each district inside Hillingdon.
Recorded floodsPast floods mapped in Hillingdon
The Environment Agency has mapped flood outlines on 24 dates in postcode districts that mostly lie in Hillingdon since 1959; the most recent started on 22 Sep 2024.
1950s 1 1970s 1 1980s 2 1990s 1 2000s 6 2010s 7 2020s 6
| Started | Place / name in the record | Source of flooding | Cause | Districts |
|---|---|---|---|---|
| 22 Sep 2024 | — 4 outlines | Main river | Channel capacity exceeded (no raised defences) | HA4 |
| 20 Oct 2023 – 21 Oct 2023 | — | Main river | Channel capacity exceeded (no raised defences) | UB10 |
| 30 Jan 2021 – 3 Feb 2021 | — 4 outlines | Main river | Channel capacity exceeded (no raised defences) | UB7 |
| 29 Jan 2021 – 3 Feb 2021 | — 3 outlines | Main river | Not recorded | UB7 |
| 18 Jan 2021 – 20 Jan 2021 | — 3 outlines | Main river, drainage | Channel capacity exceeded (no raised defences) | UB7 |
| 4 Oct 2020 – 7 Oct 2020 | — 2 outlines | Main river, ordinary watercourse | Not recorded | UB7 |
| 1 Oct 2019 | — | Main river | Other | HA4 |
| 24 Sep 2019 | — | Drainage | Local drainage/surface water | HA4 |
| 24 Jun 2016 | — | Main river | Channel capacity exceeded (no raised defences) | UB7 |
| 23 Jun 2016 – 25 Jun 2016 | — 6 outlines | Main river, ordinary watercourse | Channel capacity exceeded (no raised defences) | HA4 HA6 UB7 |
| 31 Jan 2014 – 18 Feb 2014 | — 9 outlines | Main river, other | Channel capacity exceeded (no raised defences) | UB7 UB8 |
| 17 Jan 2014 | — 2 outlines | Drainage, main river | Local drainage/surface water | UB8 |
| 23 Dec 2013 – 24 Dec 2013 | — | Main river | Channel capacity exceeded (no raised defences) | UB7 |
| 30 Nov 2009 | — 5 outlines | Main river | Channel capacity exceeded (no raised defences) | HA4 |
| 9 Feb 2009 – 10 Feb 2009 | — 3 outlines | Main river, other | Channel capacity exceeded (no raised defences) | UB7 |
| 28 May 2007 – 29 May 2007 | — | Main river | Channel capacity exceeded (no raised defences) | UB10 |
| 1 Jan 2003 – 2 Jan 2003 | — | Main river | Channel capacity exceeded (no raised defences) | UB7 |
| 23 Dec 2002 – 12 Jan 2003 | — 66 outlines | Sewer, main river | Channel capacity exceeded (no raised defences) | TW6 UB7 |
| 1 Jan 2000 – 12 Dec 2000 | — | Main river | Channel capacity exceeded (no raised defences) | UB7 |
| 1 Jan 1999 – 31 Dec 1999 | — 4 outlines | Main river, sewer | Channel capacity exceeded (no raised defences) | HA4 UB10 |
| 1 Jan 1988 – 12 Dec 1988 | — | Main river | Channel capacity exceeded (no raised defences) | UB10 |
| 1 Jan 1987 – 12 Dec 1987 | — 27 outlines | Main river | Channel capacity exceeded (no raised defences) | UB10 UB7 UB8 |
| 1 Jan 1977 – 12 Dec 1977 | — | Main river | Channel capacity exceeded (no raised defences) | UB10 |
| 1 Jan 1959 – 12 Dec 1959 | — | Not recorded | Channel capacity exceeded (no raised defences) | HA4 |
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.
"Hillingdon" means the local authority area (ONS code E09000017), not only the town centre.
If you live in Hillingdon
- Check your own address on gov.uk; it also covers surface water.
- Sign up for free flood warnings: gov.uk/get-flood-warnings. Floodline: 0345 988 1188.
- What is in force now: flood warnings UK · river levels.
- Never walk or drive through flood water: why shallow water kills.
FAQQuestions people ask
Is Hillingdon at risk of flooding?
In Hillingdon, 2,383 of 135,669 properties (1.8%) 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 ranks 93rd of 296 local authorities in England by number.
Which parts of Hillingdon have the most properties at flood risk?
Postcode district HA4 has the most: 745 properties at high or medium risk (3.2% of its properties in Hillingdon). The table on this page lists every district.
When did Hillingdon last flood?
The Environment Agency has mapped flood outlines on 24 dates in postcode districts that mostly lie in Hillingdon since 1959; the most recent started on 22 Sep 2024.
Does this include surface water flooding?
No. These counts cover flooding from rivers and the sea only. Surface water (heavy rain) flooding affects more properties in England; check it for one address on gov.uk's long-term flood risk service.
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.