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B−Hazard risk Grade
Flood & hazards in Norwich · Environment Agency

In Norwich, heavy rain puts more homes at risk than rivers or the sea: 4.3%, against 0.3%

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. Hazard risk puts Norwich at B−: #33 of 51 in Norfolk.

1912worst recorded flood68flood warnings since 20062.8%at low risk
In brief

What stands out about Norwich’s hazards

From the Environment Agency’s maps and records and the BGS radon atlas, below.

Rain, more than the river4.3% of homes sit where heavy rain can flood the streets, against 0.3% at risk from rivers and the sea.Remembers 1912Floodwater covered 175 hectares of today’s Norwich in 1912; 3,993 of today’s households live inside past flood outlines.68 flood warnings since 2006For the parts of Norwich the Environment Agency warns directly; the most recent on 10 December 2025.
By hazard

What Norwich faces

Each hazard against its own yardstick; meters run from low to high on that yardstick.

Rivers and the sea

0.3%of homes at high or medium risk
More than the typical UK town · more than 54% of towns
369 homes by the EA’s own count

Surface water

4.3%of homes at high or medium risk
More than 60% of UK towns
Rivers and sea: 0.3%

Past floods

3years with a recorded flood
Last recorded: November 1993
3,993 households inside past outlines

Flood warnings

68flood warnings since 2006
374 flood alerts for the wider area
Last warning 10 December 2025

Radon

2%of the city in a radon Affected Area
Highest band here: 1–3% of homes
No square of 5% or more
Not on this page: coastal erosion, subsidence and shrink-swell ground (the British Geological Survey licenses it), groundwater flooding and reservoir failure.
Hazard risk Grade

Norwich grades B− for hazard risk

Flood risk from rivers and the sea, against all UK towns.

Homes at high or medium flood risk (0.3%)Fewer than 46% of 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.

Flood map

Where the water goes in Norwich

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.

Recorded flood: 1912Recorded flood: 1968Recorded flood: 1993© OpenStreetMap contributors · EA NaFRA2
HighMediumLowrivers & seaHighMediumLowsurface waterNorwich’s built-up area

The river and sea risk follows the River Yare, the Tud and the Wensum. Surface-water risk is spread across the city, in dips, underpasses and along small streams, which is why more homes are exposed to it.

Rivers and the sea

0.3% of Norwich’s homes are at high or medium risk from rivers or the sea

The Environment Agency’s national map, allowing for defences. A further 2.8% are at low risk.

High riskunder 0.1%of homes · 1 in 30 a year or more56 homes, EA count
Medium risk0.3%of homes · 1 in 30 to 1 in 100313 homes, EA count
Low risk2.8%of homes · 1 in 100 to 1 in 1,0002,946 homes, EA count
Where Norwich sits among 3,735 UK towns
35%None
23%Under 0.5%Norwich
9%0.5–1%
11%1–2%
11%2–5%
5%5–10%
3%10–20%
2%20% +

Share of each UK town’s homes at high or medium risk from rivers and the sea. 35% of UK towns have none; Norwich has more than 54% of towns.

Towns its size: 14th of 48 from the fewest homes at risk
#TownPeopleHigh or med.
1Islington London216,3090%
2Camden London209,3420%
3Westminster London203,5710%
…
12Kingswood and Fishponds Gloucestershire160,2800.2%
13Bournemouth Dorset196,4530.3%
14Norwich Norfolk200,7440.3%
15Northampton Northamptonshire243,5270.3%
16Southend-on-Sea Essex182,2950.4%
…
47Oxford Oxfordshire170,7994.7%
48Kingston upon Hull East Riding of Yorkshire270,8166.3%

UK towns of 141,000 to 281,000 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.

Surface water

Heavy rain puts about 12.9 times as many Norwich 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.

Surface water4.3%
Rivers and the sea0.3%
0%7%14% of homes

About 2.1% of homes are at high risk of surface-water flooding (a 1 in 30 chance or more each year) and 2.2% at medium risk: roughly 3,840 households. A further 6.7% face a low risk from surface water. That is more than 60% of UK towns.

~3,840
households at high or medium risk
6.7%
of homes at low risk
60%
of UK towns have a smaller share
120,281
addresses read on the map

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.

Flood history

Norwich has flooded in 3 recorded years since 1912, most of all in 1912

Every flood the Environment Agency has mapped inside Norwich’s built-up area, newest first. The record is fullest for big river floods; small and surface-water floods are often missing.

  1. 1993November 1993: River flooding recorded1 hectare inside today’s built-up area · Fluival Flood
  2. 1968January 1968: River flooding recorded12 hectares inside today’s built-up area · September Flood
  3. 1912September 1912: River flooding recorded175 hectares inside today’s built-up area · Norwich Flood
The worst: 1912175 ha

Floodwater covered 175 hectares of what is now Norwich in 1912, the largest flood the record holds here (September).

3,993 of Norwich’s households today live inside the outline of a recorded flood.

Since 1912, the largest recorded flood inside the city covered 12 hectares.

Flood warnings

No flood warning or alert is in force for Norwich · 68 warnings in 20 years

The Environment Agency has 8 flood warning areas and 5 alert areas reaching into the city; warnings since the service began in 2006.

Now: no flood warnings or alerts for Norwich (checked 5 November 2026, 19:44). Check for flooding on GOV.UK →
Warnings and alerts each year for areas in Norwich
06
07
08
09
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
Flood warning (flooding expected)Flood alert (flooding possible)

The warning area covering the most of Norwich, The River Wensum, through Norwich, has not had a flood warning since 2006. Of the 68 warnings, 44 were for Riverside properties along the tidal River Yare including Cantley, Brundall and Reedham and 12 for The River Yare from Barnham Broom to the A11 at Cringleford.

2024 had the most warnings (16). The most recent warning was on 10 December 2025.

Show the 13 warning and alert areas
AreaKindSince 2006Now
Riverside properties along the tidal River Yare including Cantley, Brundall and ReedhamWarning area44None
The River Yare from Barnham Broom to the A11 at CringlefordWarning area12None
The tidal River Yare from Thorpe St Andrew to LoddonWarning area5None
The River Yare from the A11 at Cringleford to Trowse NewtonWarning area4None
The River Wensum from Swanton Morley to CostesseyWarning area1None
The River Tud from East Dereham to New CostesseyWarning area1None
Riverside properties on the River Wensum, through NorwichWarning area1None
The River Wensum, through NorwichWarning area0None
The tidal River Yare from Thorpe St Andrew to Breydon WaterAlert area270None
The upper Rivers Yare, Tiffey, Tas and WactonAlert area46None
The Rivers Tud and Wensum from Fakenham to Costessey, including Wendling BeckAlert area29None
The River Yare at Norwich, from Cringleford to Trowse NewtonAlert area19None
The River Wensum from New Costessey to Thorpe Bridge at NorwichAlert area10None

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.

Radon

Parts of Norwich are in radon Affected Areas, at the low end

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).

TG1410: Under 1% of homes above the action levelTG1509: Under 1% of homes above the action levelTG1510: Under 1% of homes above the action levelTG1511: Under 1% of homes above the action levelTG1609: Under 1% of homes above the action levelTG1610: Under 1% of homes above the action levelTG1611: Under 1% of homes above the action levelTG1708: Under 1% of homes above the action levelTG1709: Under 1% of homes above the action levelTG1710: Under 1% of homes above the action levelTG1711: Under 1% of homes above the action levelTG1807: Under 1% of homes above the action levelTG1808: Under 1% of homes above the action levelTG1809: Under 1% of homes above the action levelTG1810: Under 1% of homes above the action levelTG1811: Under 1% of homes above the action levelTG1906: Under 1% of homes above the action levelTG1907: Under 1% of homes above the action levelTG1908: Under 1% of homes above the action levelTG1909: Under 1% of homes above the action levelTG1910: Under 1% of homes above the action levelTG1911: Under 1% of homes above the action levelTG1912: Under 1% of homes above the action levelTG1913: Under 1% of homes above the action levelTG2005: Under 1% of homes above the action levelTG2006: Under 1% of homes above the action levelTG2007: Under 1% of homes above the action levelTG2008: Under 1% of homes above the action levelTG2009: Under 1% of homes above the action levelTG2010: Under 1% of homes above the action levelTG2011: Under 1% of homes above the action levelTG2012: Under 1% of homes above the action levelTG2013: Under 1% of homes above the action levelTG2014: Under 1% of homes above the action levelTG2105: Under 1% of homes above the action levelTG2106: Under 1% of homes above the action levelTG2107: Under 1% of homes above the action levelTG2108: Under 1% of homes above the action levelTG2109: Under 1% of homes above the action levelTG2110: Under 1% of homes above the action levelTG2111: Under 1% of homes above the action levelTG2112: Under 1% of homes above the action levelTG2113: Under 1% of homes above the action levelTG2114: Under 1% of homes above the action levelTG2205: Under 1% of homes above the action levelTG2206: Under 1% of homes above the action levelTG2207: Under 1% of homes above the action levelTG2208: Under 1% of homes above the action levelTG2209: Under 1% of homes above the action levelTG2210: Under 1% of homes above the action levelTG2211: Under 1% of homes above the action levelTG2212: Under 1% of homes above the action levelTG2213: Under 1% of homes above the action levelTG2214: Under 1% of homes above the action levelTG2305: Under 1% of homes above the action levelTG2306: Under 1% of homes above the action levelTG2307: Under 1% of homes above the action levelTG2308: Under 1% of homes above the action levelTG2309: Under 1% of homes above the action levelTG2310: Under 1% of homes above the action levelTG2311: Under 1% of homes above the action levelTG2312: Under 1% of homes above the action levelTG2313: Under 1% of homes above the action levelTG2314: Under 1% of homes above the action levelTG2406: Under 1% of homes above the action levelTG2407: Under 1% of homes above the action levelTG2408: Under 1% of homes above the action levelTG2409: Under 1% of homes above the action levelTG2410: Under 1% of homes above the action levelTG2411: Under 1% of homes above the action levelTG2412: Under 1% of homes above the action levelTG2413: Under 1% of homes above the action levelTG2507: Under 1% of homes above the action levelTG2508: Under 1% of homes above the action levelTG2509: Under 1% of homes above the action levelTG2510: Under 1% of homes above the action levelTG2511: Under 1% of homes above the action levelTG2512: Under 1% of homes above the action levelTG2608: Under 1% of homes above the action levelTG2609: Under 1% of homes above the action levelTG2610: Under 1% of homes above the action levelTG2611: Under 1% of homes above the action levelTG2612: Under 1% of homes above the action levelTG2708: 1–3% of homes above the action levelTG2709: Under 1% of homes above the action levelTG2710: Under 1% of homes above the action levelTG2711: Under 1% of homes above the action levelTG2808: 1–3% of homes above the action levelTG2809: Under 1% of homes above the action levelTG2810: Under 1% of homes above the action levelTG2908: Under 1% of homes above the action levelTG2909: Under 1% of homes above the action level© OpenStreetMap contributors · BGS/UKHSA
Under 1%1–3%
Share of the city’s area in each band
Under 1% of homes98%
1–3% of homes2%

2% of Norwich’s built-up area is in a radon Affected Area (1% of homes or more above the action level).

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.

Neighbours

Flood risk in the places around Norwich

Share of homes at high or medium and at low risk from rivers and the sea. Tap a town for its page.

Cringleford: Hazard risk B+Thorpe End: Hazard risk ACostessey: Hazard risk B−Horsham St Faith: Hazard risk ASpixworth: Hazard risk ARackheath: Hazard risk ATaverham and Drayton: Hazard risk BCringlefordThorpe EndCostesseyHorsham St FaithSpixworthRackheathTaverham and DraytonNorwich
ABCD
TownPeopleHigh or mediumLowHazard
Norwich200,7440.3%2.8%B−
Cringleford4,6860%under 0.1%B+
Thorpe End1,1730%0%A
Costessey2,6080.3%4.7%B−
Horsham St Faith1,0510%0%A
Spixworth3,4180%0%A
Rackheath1,7610%0%A
Taverham and Drayton14,989under 0.1%0.1%B

Norwich has more homes at high or medium risk than any neighbour in the table.

Be ready

Get ready for what Norwich faces

Free warnings, what to do in a cloudburst, and what to check before you move.

Get the warnings
  • Sign up free for Environment Agency flood warnings by text, call or email.
  • Floodline: 0345 988 1188, 24 hours.
  • Norwich’s warning areas include The River Wensum, through Norwich and Riverside properties on the River Wensum, through Norwich.
Sign up ↗
In a cloudburst
  • 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.
Radon
  • 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%.
UKradon ↗
Before you buy or rent in Norwich
  • 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.
How to read these numbers

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.

Check the long-term flood risk for an address on GOV.UK →

Questions about flooding and hazards in Norwich

Does Norwich flood?

The last flood the Environment Agency recorded inside the city was in November 1993. 0.3% 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 4.3% of homes are at high or medium risk from surface water, when heavy rain overwhelms the drains. Norwich grades B− for hazard risk against UK towns.

Which parts of Norwich are at risk of flooding?

From rivers and the sea, the places the Environment Agency warns directly: Riverside properties along the tidal River Yare including Cantley, Brundall and Reedham, The River Yare from Barnham Broom to the A11 at Cringleford, The tidal River Yare from Thorpe St Andrew to Loddon and The River Yare from the A11 at Cringleford to Trowse Newton. 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 Norwich last flood?

The recorded flood outlines inside the city run from 1912 to 1993 (3 years); the largest was in 1912. Flood warnings have been issued for parts of the city since 2006, most recently on 10 December 2025.

Is Norwich at risk of surface water flooding?

About 2.1% of homes are at high risk and 2.2% at medium risk from surface water, against 0.3% 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 Norwich?

2% of the city’s built-up area is in a radon Affected Area on the BGS/UKHSA atlas. Most homes are below it; a three-month test is the only way to know.

Are there flood warnings in Norwich now?

No flood warning or alert was in force near Norwich at 5 November 2026, 19:44. 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 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.