Photo: SuzanneKn at en.wikipedia · Public domainIn West End and Chobham, heavy rain puts more homes at risk than rivers or the sea: 4.4%, against 0.8%
On the Environment Agency’s maps, which allow for flood defences, “high or medium” means at least a 1 in 100 chance of flooding from rivers or the sea in any year. For hazard risk, West End and Chobham grades C: #33 of 65 in Surrey.
What stands out about West End and Chobham’s hazards
From the Environment Agency’s maps and records and the BGS radon atlas, below.
What West End and Chobham faces
Each hazard against its own yardstick; meters run from low to high on that yardstick.
Rivers and the sea
Surface water
Past floods
The Addlestone Bourne
Flood warnings
Radon
West End and Chobham grades C for hazard risk
Flood risk from rivers and the sea, against all UK towns.
The share of homes at high or medium risk from rivers and the sea, ranked against every UK town of 1,000 or more: fewer homes at risk is better. Towns with none at high or medium risk are ordered by their share at low risk, so they don’t all share one score. Surface water and radon aren’t graded: they are described below.
Where the water goes in West End and Chobham
Turn layers on and off. Blue is the risk from rivers and the sea; pink is where heavy rain collects. Both allow for flood defences.
The river and sea risk follows the Hale Bourne, the Windle Brook and the Mill Bourne. Surface-water risk is spread across the town, in dips, underpasses and along small streams, which is why more homes are exposed to it.
0.8% of West End and Chobham’s homes are at high or medium risk from rivers or the sea
The Environment Agency’s national map, allowing for defences. A further 1.6% are at low risk.
Share of each UK town’s homes at high or medium risk from rivers and the sea. 35% of UK towns have none; West End and Chobham has more than 65% of towns.
| # | Town | People | High or med. | |
|---|---|---|---|---|
| 1 | Desborough Northamptonshire | 11,899 | 0% | |
| 2 | Codsall Staffordshire | 11,867 | 0% | |
| 3 | Buckhurst Hill Essex | 11,749 | 0% | |
| … | ||||
| 318 | Tidworth Wiltshire | 10,693 | 0.8% | |
| 319 | Torpoint Cornwall | 7,163 | 0.8% | |
| 320 | West End and Chobham Surrey | 8,877 | 0.8% | |
| 321 | Stansted Mountfitchet Essex | 8,629 | 0.8% | |
| 322 | Sprotbrough South Yorkshire | 7,546 | 0.9% | |
| … | ||||
| 481 | East Wittering West Sussex | 6,060 | 22% | |
| 482 | Old Windsor and Wraysbury Berkshire | 7,689 | 37% | |
UK towns of 6,000 to 12,000 people.
The Environment Agency’s Risk of Flooding from Rivers and Sea (NaFRA2, June 2026) counts each postcode’s homes by band; the shares weight those postcodes by Census 2021 households. The EA counts include homes built since 2021.
Heavy rain puts about 5.3 times as many West End and Chobham homes at risk as rivers and the sea do
Surface water is rain that falls faster than drains and the ground can take it. It is mapped separately from rivers and the sea, and it is not in the Hazard risk Grade.
About 3.4% of homes are at high risk of surface-water flooding (a 1 in 30 chance or more each year) and 1% at medium risk: roughly 160 households. A further 3.2% face a low risk from surface water. That is more than 61% of UK towns.
Our estimate: every address in the town (ONS NSUL) read on the Environment Agency’s Risk of Flooding from Surface Water map (NaFRA2, 2025), each postcode’s share weighted by its Census 2021 households. Neither agency publishes a count of homes for surface water, so treat it as a guide; one street can differ from the next.
West End and Chobham has flooded in 1 recorded year since 1968
Every flood the Environment Agency has mapped inside West End and Chobham’s built-up area, newest first. The record is fullest for big river floods; small and surface-water floods are often missing.
- 1968January 1968: River flooding recorded28 hectares inside today’s built-up area
Floodwater covered 28 hectares of what is now West End and Chobham in 1968, the largest flood the record holds here (January).
92 of West End and Chobham’s households today live inside the outline of a recorded flood.
The Addlestone Bourne at Grants Bridge: highest 2.50 m, in August 2006
The highest level each winter (October to September) at the Environment Agency’s Grants Bridge gauge (Chobham), since 1998. The river normally runs between 0.33 m and 1.55 m here.
- 14 August 20062.50 m
- 20 July 20071.83 m
- 30 October 20001.81 m
- 10 February 20091.71 m
- 5 January 20241.62 m
- 25 December 19991.46 m
The Addlestone Bourne has topped its normal range on 8 days since 1998, most in the winters of 2000–01 and 2005–06. By its highest day, the winter of 2025–26 was the 19th-highest of the 26.
Environment Agency Hydrology API, Grants Bridge (station 2976TH), daily maximum level; the record and normal range from the EA’s stage scale. Live river levels are on GOV.UK’s Check for flooding.
No flood warning or alert is in force for West End and Chobham · 0 warnings in 20 years
The Environment Agency has 2 flood warning areas and 1 alert area reaching into the town; warnings since the service began in 2006.
None of West End and Chobham’s 2 flood warning areas has had a flood warning since the service began in 2006.
Show the 3 warning and alert areas
| Area | Kind | Since 2006 | Now |
|---|---|---|---|
| Hale Bourne from the M3 to Clappers Lane | Warning area | 0 | None |
| Hale Bourne and Addlestone Bourne at Chobham | Warning area | 0 | None |
| Windle Brook and Hale, Mill and Addlestone Bournes | Alert area | 36 | None |
Environment Agency Historic Flood Warnings (first issues only, not updates; “flood watch” counted as an alert before 2011) and the real-time flood-monitoring API. Sign up for free warnings on GOV.UK or call Floodline, 0345 988 1188.
West End and Chobham is in the lowest radon band
Radon is a natural radioactive gas from the ground; long exposure raises the risk of lung cancer. The atlas gives the chance that a home in each 1 km square is above the UK action level (200 Bq/m³).
Every 1 km square over West End and Chobham is in the lowest band: fewer than 1 in 100 homes are expected to be above the action level.
BGS/UKHSA Indicative Atlas of Radon in Great Britain, version 3. Check an address at UKradon.org.
Flood risk in the places around West End and Chobham
Share of homes at high or medium and at low risk from rivers and the sea. Tap a town for its page.
| Town | People | High or medium | Low | Hazard |
|---|---|---|---|---|
| West End and Chobham | 8,877 | 0.8% | 1.6% | C |
| Bisley | 4,045 | 0% | 0% | A |
| Lightwater | 6,539 | 0.4% | 1.5% | C+ |
| Windlesham | 3,706 | 0.9% | 0.4% | C |
| Brookwood | 1,428 | 0% | 0.2% | B+ |
| Bagshot | 5,930 | 6% | 4.1% | D |
| Pirbright | 3,920 | 0.8% | 0.9% | C+ |
| Woking | 75,655 | 0.5% | 1.1% | C+ |
Bagshot, 2.7 miles north-west, has the most homes at risk around West End and Chobham (6% at high or medium). Bisley and Brookwood have none.
Get ready for what West End and Chobham faces
Free warnings, what to do in a cloudburst, and what to check before you move.
- Sign up free for Environment Agency flood warnings by text, call or email.
- Floodline: 0345 988 1188, 24 hours.
- West End and Chobham’s warning areas include Hale Bourne and Addlestone Bourne at Chobham and Hale Bourne from the M3 to Clappers Lane.
- Surface water rises in minutes, often with no warning issued: stay out of underpasses and dips.
- Keep the gullies and drains outside your home clear of leaves.
- Report a blocked road drain to the council.
- Never walk or drive through floodwater: 30 cm of moving water can float a car.
- Move valuables, papers and medicines upstairs.
- Turn off gas, electricity and water if you’re told to.
- Check the address on GOV.UK’s long-term flood risk service: it gives rivers and sea and surface water separately.
- Ask whether the home has flooded or had a flood insurance claim; the TA6 property form asks the seller.
- Homes built before 2009 can get flood cover through Flood Re, the government-backed scheme; newer homes can’t.
What this data can and can’t tell you
- Defences are counted. Both agencies’ maps allow for flood defences and the chance they are overtopped or fail, so a town behind a defence scheme can show few homes at high risk and many at low risk.
- Surface water is our estimate. Neither agency publishes a count of homes at risk from surface water, so we read each address on the map. A flat on a hill and a basement in a dip can share a postcode.
- Past floods are what was recorded. The flood outlines come from surveys, aerial photographs and reports; many small floods, and most surface-water floods, were never mapped.
- One town, many streets. Risk is street by street. Check a specific address on GOV.UK’s long-term flood risk service before you buy or rent.
Questions about flooding and hazards in West End and Chobham
Does West End and Chobham flood?
The last flood the Environment Agency recorded inside the town was in January 1968. 0.8% of homes are at high or medium risk from rivers and the sea on the Environment Agency’s maps, which allow for flood defences. About 4.4% of homes are at high or medium risk from surface water, when heavy rain overwhelms the drains. West End and Chobham grades C for hazard risk against UK towns.
Which parts of West End and Chobham are at risk of flooding?
From rivers and the sea, the places the Environment Agency warns directly: Hale Bourne and Addlestone Bourne at Chobham and Hale Bourne from the M3 to Clappers Lane. Surface water can collect in low spots anywhere in the town. Check a specific address on GOV.UK’s long-term flood risk service.
When did West End and Chobham last flood?
The recorded flood outlines inside the town run from 1968 to 1968 (1 years); the largest was in 1968.
Is West End and Chobham at risk of surface water flooding?
About 3.4% of homes are at high risk and 1% at medium risk from surface water, against 0.8% at high or medium risk from rivers and the sea. Surface water floods come with little warning, and the agencies don’t issue warnings for them.
Is radon a problem in West End and Chobham?
Not by the atlas: every 1 km square over West End and Chobham is in the lowest band, where fewer than 1 in 100 homes are expected to be above the action level.
Are there flood warnings in West End and Chobham now?
No flood warning or alert was in force near West End and Chobham at 12 November 2026, 00:51. Live warnings are on GOV.UK’s Check for flooding service and Floodline, 0345 988 1188.
Contains Environment Agency information © Environment Agency and/or database right 2026. Contains British Geological Survey materials © UKRI 2026.
Sources: Environment Agency Risk of Flooding from Rivers and Sea, postcodes in areas at risk (June 2026); Natural Resources Wales Flood Risk Assessment Wales (May 2026); ONS Census 2021 households by postcode · Environment Agency Risk of Flooding from Surface Water (NaFRA2, 2025) and Natural Resources Wales Flood Risk Assessment Wales surface water and small watercourses, read at every address (ONS National Statistics UPRN Lookup, September 2026) and weighted by Census 2021 households by postcode · Environment Agency Recorded Flood Outlines and Natural Resources Wales historic flood map, inside the ONS 2022 built-up-area boundary · Environment Agency Hydrology API (daily maximum river level) and flood-monitoring stage scales · Environment Agency real-time flood-monitoring API · Environment Agency Historic Flood Warnings (January 2006 to June 2026) and flood warning and alert areas · BGS/UKHSA Indicative Atlas of Radon in Great Britain, version 3, by 1 km square · TownRatings grades: our own summary of the data, ranked against UK towns only. All under the Open Government Licence v3.0.
Contains public sector information licensed under the Open Government Licence v3.0. Contains HM Land Registry data © Crown copyright and database right 2026. Contains OS data © Crown copyright and database right 2026 (ONS boundaries). Northern Ireland: Source: NISRA; contains Land & Property Services data and Ordnance Survey of Northern Ireland information, © Crown copyright, licensed under the Open Government Licence v3.0. Scotland: contains National Records of Scotland data, Registers of Scotland data and SEPA data, © Crown copyright / © SEPA 2025, licensed under the Open Government Licence v3.0.