Photo: Mat Fascione · CC BY-SA 2.0In Gloucester, heavy rain puts more homes at risk than rivers or the sea: 10%, against 4.5%
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, Gloucester grades D: #45 of 48 in Gloucestershire.
What stands out about Gloucester’s hazards
From the Environment Agency’s maps and records and the BGS radon atlas, below.
What Gloucester 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 Severn
Flood warnings
Radon
Gloucester 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 Gloucester
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 Severn Estuary, the River Severn and the Daniels Brook. Surface-water risk is spread across the city, in dips, underpasses and along small streams, which is why more homes are exposed to it.
4.5% of Gloucester’s homes are at high or medium risk from rivers or the sea
The Environment Agency’s national map, allowing for defences. A further 2.3% 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; Gloucester has more than 89% of towns.
| # | Town | People | High or med. | |
|---|---|---|---|---|
| 1 | Oldham Greater Manchester | 110,722 | 0% | |
| 2 | Birkenhead Merseyside | 109,854 | 0% | |
| 3 | Kensington and Chelsea London | 143,348 | under 0.1% | |
| … | ||||
| 53 | Chester Cheshire | 92,756 | 3.3% | |
| 54 | York North Yorkshire | 141,696 | 4.3% | |
| 55 | Gloucester Gloucestershire | 118,562 | 4.5% | |
| 56 | Preston Lancashire | 94,502 | 4.7% | |
| 57 | Bath Somerset | 94,080 | 5.6% | |
| 58 | Lincoln Lincolnshire | 104,553 | 6% | |
| 59 | Grimsby Lincolnshire | 85,915 | 8.9% | |
UK towns of 83,000 to 166,000 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 2.2 times as many Gloucester 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 5.4% of homes are at high risk of surface-water flooding (a 1 in 30 chance or more each year) and 4.7% at medium risk: roughly 5,060 households. A further 12% face a low risk from surface water. That is more than 92% of UK towns.
Our estimate: every address in the city (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.
Gloucester has flooded in 8 recorded years since 1939, most of all in 1947
Every flood the Environment Agency has mapped inside Gloucester’s built-up area, newest first. The record is fullest for big river floods; small and surface-water floods are often missing.
- 2007July 2007: The River Twyver, the Whaddon Brook and the Daniels Brook overflowed104 hectares inside today’s built-up area
- 2001January 2001: The River Severn overflowed8 hectares inside today’s built-up area
- 2000October and December 2000: River flooding recorded28 hectares inside today’s built-up area · Lower Severn
- 1990January and February 1990: River flooding recorded24 hectares inside today’s built-up area
- 1988March 1988: River flooding recordedUnder 1 hectare inside today’s built-up area
- 1968July 1968: River flooding recorded11 hectares inside today’s built-up area · Lower Severn
Show all 8
- 1947March 1947: The River Severn overflowed142 hectares inside today’s built-up area · Lower Severn
- 1939January 1939: River flooding recorded21 hectares inside today’s built-up area · Lower Severn
The River Severn covered 142 hectares of what is now Gloucester in 1947, the largest flood the record holds here (March).
2,502 of Gloucester’s households today live inside the outline of a recorded flood.
Since 1947, the largest recorded flood inside the city covered 104 hectares.
The River Severn at Gloucester: highest 4.92 m, in July 2007
The highest level each winter (October to September) at the Environment Agency’s Gloucester gauge, since 1990. The river normally runs between 0.44 m and 3.20 m here.
- 13 August 202232.77 m
- 21 August 202232.77 m
- 29 August 202232.77 m
- 6 September 202232.77 m
- 14 September 202232.77 m
- 22 September 202232.77 m
The River Severn has topped its normal range on 754 days since 1990, most in the winters of 2021–22 and 2019–20. By its highest day, the winter of 2025–26 was the 23rd-highest of the 34.
Environment Agency Hydrology API, Gloucester (station 2165), 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 Gloucester · 90 warnings in 20 years
The Environment Agency has 10 flood warning areas and 3 alert areas reaching into the city; warnings since the service began in 2006.
The warning area covering the most of Gloucester, Whaddon Brook at Lower Tuffley, has not had a flood warning since 2006. Of the 90 warnings, 43 were for River Severn at Sandhurst and Maisemore and 17 for River Severn at Minsterworth and Stonebench.
2014 had the most warnings (16); 2024 the most alerts (31). The most recent warning was on 23 February 2026.
Show the 13 warning and alert areas
| Area | Kind | Since 2006 | Now |
|---|---|---|---|
| River Severn at Sandhurst and Maisemore | Warning area | 43 | None |
| River Severn at Minsterworth and Stonebench | Warning area | 17 | None |
| River Severn at Hempsted | Warning area | 11 | None |
| River Severn at Gloucester | Warning area | 8 | None |
| Daniels Brook at Lower Tuffley | Warning area | 3 | None |
| Horesbere Brook at Gloucester | Warning area | 3 | None |
| River Twyver at Gloucester | Warning area | 2 | None |
| Sud Brook at Gloucester | Warning area | 2 | None |
| Wotton Brook at Gloucester | Warning area | 1 | None |
| Whaddon Brook at Lower Tuffley | Warning area | 0 | None |
| Severn estuary from Gloucester to Sharpness | Alert area | 115 | None |
| River Severn in Gloucestershire | Alert area | 105 | None |
| Tributaries in Gloucester | Alert area | 78 | 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.
Parts of Gloucester are in radon Affected Areas, up to the 10–30% 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).
12% of Gloucester’s built-up area is in a radon Affected Area (1% of homes or more above the action level), and 6% in squares of 5% or more, mostly on the south side of the city.
The squares are indicative: each takes the highest band found anywhere inside it, so most homes in a coloured square are below it. Only a three-month test in the home gives a real answer.
BGS/UKHSA Indicative Atlas of Radon in Great Britain, version 3. Check an address at UKradon.org.
Flood risk in the places around Gloucester
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 |
|---|---|---|---|---|
| Gloucester | 118,562 | 4.5% | 2.3% | D |
| Upton St Leonards | 1,132 | 0% | 0.6% | B+ |
| Longford | 2,536 | 8.3% | 11% | D |
| Brockworth | 12,007 | 0.1% | 0.3% | B− |
| Churchdown | 13,480 | under 0.1% | 0.1% | B |
| Quedgeley and Hardwicke | 21,125 | 0.4% | 0.8% | C+ |
| Highnam | 1,920 | 0% | 0% | A |
| Shurdington | 1,888 | 0% | 0% | A |
Longford, 2.2 miles north, has the most homes at risk around Gloucester (8.3% at high or medium). Upton St Leonards, Highnam and Shurdington have none.
Get ready for what Gloucester 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.
- Gloucester’s warning areas include Wotton Brook at Gloucester and River Severn at Gloucester.
- 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.
- Test over three months, in a living room and a bedroom.
- Above 200 Bq/m³, a small sump and fan usually fixes it.
- New homes in radon areas are built with protection: basic from 3%, full from 10%.
- 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.
- Check radon for the address on UKradon.org (a small fee) or ask the seller for a test result.
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 Gloucester
Does Gloucester flood?
The last flood the Environment Agency recorded inside the city was in July 2007. 4.5% 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 10% of homes are at high or medium risk from surface water, when heavy rain overwhelms the drains. Gloucester grades D for hazard risk against UK towns.
Which parts of Gloucester are at risk of flooding?
From rivers and the sea, the places the Environment Agency warns directly: River Severn at Sandhurst and Maisemore, River Severn at Minsterworth and Stonebench, River Severn at Hempsted and River Severn at Gloucester. Surface water can collect in low spots anywhere in the city. Check a specific address on GOV.UK’s long-term flood risk service.
When did Gloucester last flood?
The recorded flood outlines inside the city run from 1939 to 2007 (8 years); the largest was in 1947. Flood warnings have been issued for parts of the city since 2006, most recently on 23 February 2026.
Is Gloucester at risk of surface water flooding?
About 5.4% of homes are at high risk and 4.7% at medium risk from surface water, against 4.5% 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 Gloucester?
12% of the city’s built-up area is in a radon Affected Area on the BGS/UKHSA atlas, and 6% is in 1 km squares where 5% or more of homes may be above the action level. Most homes are below it; a three-month test is the only way to know.
Are there flood warnings in Gloucester now?
No flood warning or alert was in force near Gloucester at 5 November 2026, 19:28. 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.