Photo: James Emmans · CC BY-SA 2.0Addlestone is a river town: 7.8% of its homes are at high or medium risk from rivers or the sea, more than in 94% of UK towns
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. Addlestone grades D for hazard risk: #57 of 65 in Surrey.
What stands out about Addlestone’s hazards
From the Environment Agency’s maps and records and the BGS radon atlas, below.
What Addlestone 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 River Wey
Flood warnings
Radon
Addlestone grades D 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 Addlestone
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 River Wey, the East Clandon Stream and the Windle Brook. Surface-water risk is patchier: dips, underpasses and small streams.
7.8% of Addlestone’s homes are at high or medium risk from rivers or the sea
The Environment Agency’s national map, allowing for defences. A further 13% 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; Addlestone has more than 94% of towns.
| # | Town | People | High or med. | |
|---|---|---|---|---|
| 1 | Litherland Merseyside | 18,752 | 0% | |
| 2 | Clifton Greater Manchester | 17,748 | 0% | |
| 3 | Oswestry Shropshire | 17,500 | 0% | |
| … | ||||
| 342 | Wells Somerset | 12,097 | 7% | |
| 343 | South Hayling Hampshire | 15,305 | 7.4% | |
| 344 | Addlestone Surrey | 13,748 | 7.8% | |
| 345 | Hythe Kent | 14,613 | 8.2% | |
| 346 | Scawthorpe and Cusworth South Yorkshire | 13,020 | 8.5% | |
| … | ||||
| 359 | Bentley South Yorkshire | 12,044 | 40% | |
| 360 | Dunscroft and Hatfield South Yorkshire | 14,000 | 51% | |
UK towns of 10,000 to 19,000 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.
Rivers and the sea, more than heavy rain, are Addlestone’s flood risk
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 1.6% of homes are at high risk of surface-water flooding (a 1 in 30 chance or more each year) and 2.5% at medium risk: roughly 250 households. A further 6.1% face a low risk from surface water. That is more than 57% 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.
Addlestone has flooded in 5 recorded years since 1947, most of all in 1968
Every flood the Environment Agency has mapped inside Addlestone’s built-up area, newest first. The record is fullest for big river floods; small and surface-water floods are often missing.
- 2013November 2013: River flooding recorded5 hectares inside today’s built-up area
- 2002December 2002: River flooding recorded13 hectares inside today’s built-up area
- 1974January 1974: River flooding recorded31 hectares inside today’s built-up area
- 1968January 1968: River flooding recorded41 hectares inside today’s built-up area
- 1947January 1947: River flooding recorded34 hectares inside today’s built-up area
Floodwater covered 41 hectares of what is now Addlestone in 1968, the largest flood the record holds here (January).
905 of Addlestone’s households today live inside the outline of a recorded flood.
Since 1968, the largest recorded flood inside the town covered 31 hectares.
The River Wey at Weybridge: highest 1.93 m, in November 2000
The highest level each winter (October to September) at the Environment Agency’s Weybridge gauge (Weybridge), since 1990. The river normally runs between 0.96 m and 1.40 m here.
- 8 November 20001.93 m
- 26 December 20131.88 m
- 1 November 20001.67 m
- 4 February 19901.64 m
- 3 January 20031.62 m
- 18 February 20201.60 m
The River Wey has topped its normal range on 46 days since 1990, most in the winters of 2013–14 and 2000–01. By its highest day, the winter of 2025–26 was the 5th-highest of the 36.
Environment Agency Hydrology API, Weybridge (station 3090TH), 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 Addlestone · 7 warnings in 20 years
The Environment Agency has 5 flood warning areas and 3 alert areas reaching into the town; warnings since the service began in 2006.
Of the 7 warnings, 4 were for River Wey at Weybridge and 2 for Areas of Chertsey closest to the Chertsey Bourne. 2014 had the most warnings (3); 2024 the most alerts (20).
The most recent warning was on 6 February 2026.
Show the 8 warning and alert areas
| Area | Kind | Since 2006 | Now |
|---|---|---|---|
| River Wey at Weybridge | Warning area | 4 | None |
| Areas of Chertsey closest to the Chertsey Bourne | Warning area | 2 | None |
| Addlestone Bourne at Addlestone | Warning area | 1 | None |
| Addlestone Bourne at Woodham | Warning area | 0 | None |
| Properties closest to the Addlestone Bourne at Addlestone | Warning area | 0 | None |
| Chertsey Bourne | Alert area | 72 | None |
| Windle Brook and Hale, Mill and Addlestone Bournes | Alert area | 36 | None |
| Lower River Wey | Alert area | 25 | 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.
Addlestone 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 Addlestone 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 Addlestone
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 |
|---|---|---|---|---|
| Addlestone | 13,748 | 7.8% | 13% | D |
| Chertsey | 14,558 | 33% | 14% | D− |
| Weybridge | 15,918 | 3.9% | 1.8% | D |
| New Haw, West Byfleet and Sheerwater | 33,035 | 1.4% | 1.4% | C |
| Byfleet | 14,187 | 4.3% | 26% | D |
| Lyne | 1,202 | 0.3% | 0.6% | B− |
| Shepperton Green | 4,358 | 21% | 61% | D− |
| Shepperton | 5,917 | 30% | 36% | D− |
Chertsey, 1.3 miles north-west, has the most homes at risk around Addlestone (33% at high or medium).
Get ready for what Addlestone 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.
- Addlestone’s warning areas include Addlestone Bourne at Addlestone and Properties closest to the Addlestone Bourne at Addlestone.
- 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 Addlestone
Does Addlestone flood?
The last flood the Environment Agency recorded inside the town was in November 2013. 7.8% 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% of homes are at high or medium risk from surface water, when heavy rain overwhelms the drains. Addlestone grades D for hazard risk against UK towns.
Which parts of Addlestone are at risk of flooding?
From rivers and the sea, the places the Environment Agency warns directly: River Wey at Weybridge, Areas of Chertsey closest to the Chertsey Bourne, Addlestone Bourne at Addlestone and Properties closest to the Addlestone Bourne at Addlestone. 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 Addlestone last flood?
The recorded flood outlines inside the town run from 1947 to 2013 (5 years); the largest was in 1968. Flood warnings have been issued for parts of the town since 2006, most recently on 6 February 2026.
Is Addlestone at risk of surface water flooding?
About 1.6% of homes are at high risk and 2.5% at medium risk from surface water, against 7.8% 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 Addlestone?
Not by the atlas: every 1 km square over Addlestone 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 Addlestone now?
No flood warning or alert was in force near Addlestone at 4 November 2026, 08:08. 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.