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C−Hazard risk Grade
Flood & hazards in Bromley · Environment Agency

Surface water, more than the river, is Bromley’s flood risk: 6.9% of homes, against 2% from rivers or the sea

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 Bromley at C−: #30 of 33 in London.

In brief

What stands out about Bromley’s hazards

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

By hazard

What Bromley faces

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

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

Bromley grades C− for hazard risk

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

Homes at high or medium flood risk (2%)Fewer than 21% 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 Bromley

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: 1965Recorded flood: 1968Recorded flood: 1977© OpenStreetMap contributors · EA NaFRA2
HighMediumLowrivers & seaHighMediumLowsurface waterBromley’s built-up area

The river and sea risk follows the Shuttle, the Cray and the River Quaggy. Surface-water risk is spread across the borough, in dips, underpasses and along small streams, which is why more homes are exposed to it.

Rivers and the sea

2% of Bromley’s homes are at high or medium risk from rivers or the sea

The Environment Agency’s national map, allowing for defences. A further 0.6% are at low risk.

High risk1.6%of homes · 1 in 30 a year or more2,184 homes, EA count
Medium risk0.5%of homes · 1 in 30 to 1 in 100895 homes, EA count
Low risk0.6%of homes · 1 in 100 to 1 in 1,000944 homes, EA count
Where Bromley sits among 3,735 UK towns
35%None
23%Under 0.5%
9%0.5–1%
11%1–2%
11%2–5%Bromley
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; Bromley has more than 79% of towns.

Towns its size: 32nd of 38 from the fewest homes at risk
#TownPeopleHigh or med.
1Southwark London307,0760%
2Newham London351,065under 0.1%
3Wolverhampton West Midlands234,029under 0.1%
…
30Croydon London389,2421.9%
31Greenwich London288,1172%
32Bromley London325,4692%
33Leicester Leicestershire406,6122.1%
34Wandsworth London326,7252.1%
…
37Nottingham Nottinghamshire299,7863.6%
38Kingston upon Hull East Riding of Yorkshire270,8166.3%

UK towns of 228,000 to 456,000 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 3.4 times as many Bromley 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 water6.9%
Rivers and the sea2%
0%10.5%21% of homes

About 3.6% of homes are at high risk of surface-water flooding (a 1 in 30 chance or more each year) and 3.3% at medium risk: roughly 9,350 households. A further 7.5% face a low risk from surface water. That is more than 82% of UK towns.

~9,350
households at high or medium risk
7.5%
of homes at low risk
82%
of UK towns have a smaller share
168,674
addresses read on the map

Our estimate: every address in the borough (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

Bromley has flooded in 3 recorded years since 1965, most of all in 1968

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

  1. 1977August 1977: River flooding recorded11 hectares inside today’s built-up area
  2. 1968September 1968: River flooding recorded369 hectares inside today’s built-up area
  3. 1965November 1965: River flooding recorded87 hectares inside today’s built-up area
The worst: 1968369 ha

Floodwater covered 369 hectares of what is now Bromley in 1968, the largest flood the record holds here (September).

3,819 of Bromley’s households today live inside the outline of a recorded flood.

Since 1968, the largest recorded flood inside the borough covered 11 hectares.

River levels

The River Ravensbourne at Hayes Lane: highest 1.05 m, in December 2013

The highest level each winter (October to September) at the Environment Agency’s Hayes Lane gauge, since 1990. The river normally runs between 0.00 m and 1.80 m here.

Highest level each winter, metres
Winter 1990–91: highest 0.10 m · 0 days above the normal rangeWinter 1991–92: highest 0.10 m · 0 days above the normal rangeWinter 1992–93: highest 0.24 m · 0 days above the normal rangeWinter 1993–94: highest 0.28 m · 0 days above the normal rangeWinter 1998–99: highest 0.22 m · 0 days above the normal rangeWinter 1999–00: highest 0.26 m · 0 days above the normal rangeWinter 2000–01: highest 0.40 m · 0 days above the normal rangeWinter 2001–02: highest 1.05 m on 27 August 2002 · 0 days above the normal rangeWinter 2002–03: highest 0.41 m · 0 days above the normal rangeWinter 2003–04: highest 0.22 m · 0 days above the normal rangeWinter 2004–05: highest 0.06 m · 0 days above the normal rangeWinter 2008–09: highest 0.50 m on 13 December 2008 · 0 days above the normal rangeWinter 2009–10: highest 0.48 m on 28 February 2010 · 0 days above the normal rangeWinter 2010–11: highest 0.39 m · 0 days above the normal rangeWinter 2014–15: highest 0.28 m · 0 days above the normal rangeWinter 2015–16: highest 0.34 m · 0 days above the normal rangeWinter 2016–17: highest 0.18 m · 0 days above the normal rangeWinter 2017–18: highest 0.23 m · 0 days above the normal rangeWinter 2018–19: highest 0.48 m on 10 June 2019 · 0 days above the normal rangeWinter 2019–20: highest 0.55 m on 16 February 2020 · 0 days above the normal rangeWinter 2020–21: highest 0.52 m on 14 January 2021 · 0 days above the normal rangeWinter 2021–22: highest 0.37 m · 0 days above the normal rangeWinter 2024–25: highest 0.21 m · 0 days above the normal rangeWinter 2025–26: highest 0.29 m · 0 days above the normal range’01–02’19–20’20–21Record 1.05 m, 2013Top of normal range
1990–912025–26
The highest days on record
  • 27 August 20021.05 m
  • 16 February 20200.55 m
  • 14 January 20210.52 m
  • 20 December 20190.52 m
  • 13 December 20080.50 m
  • 10 June 20190.48 m

The River Ravensbourne has topped its normal range on 0 days since 1990. By its highest day, the winter of 2025–26 was the 12th-highest of the 24.

Environment Agency Hydrology API, Hayes Lane (station 4310TH), 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.

Flood warnings

No flood warning or alert is in force for Bromley · 14 warnings in 20 years

The Environment Agency has 10 flood warning areas and 2 alert areas reaching into the borough; warnings since the service began in 2006.

Now: no flood warnings or alerts for Bromley (checked 6 November 2026, 04:12). Check for flooding on GOV.UK →
Warnings and alerts each year for areas in Bromley
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 Bromley, Groundwater flooding in South East London, has not had a flood warning since 2006. Of the 14 warnings, 4 were for Kyd Brook at Petts Wood and 3 for Chaffinch Brook and St James Stream at Elmers End.

2013 had the most warnings (5); 2021 the most alerts (18). The most recent warning was on 27 September 2024.

Show the 12 warning and alert areas
AreaKindSince 2006Now
Kyd Brook at Petts WoodWarning area4None
River Quaggy at Chinbrook, Mottingham and ElthamWarning area3None
Chaffinch Brook and St James Stream at Elmers EndWarning area3None
Groundwater flooding in South East LondonWarning area0None
River Cray in St Marys Cray, Sidcup, Bexley and CrayfordWarning area2None
Ravensbourne at BromleyWarning area1None
Kyd Brook at Sundridge ParkWarning area1None
Beck at BeckenhamWarning area0None
Pool River at Bell Green and New BeckenhamWarning area0None
Ravensbourne from Bellingham to CatfordWarning area0None
Ravensbourne area in the London Boroughs of Lewisham, Bromley, Greenwich and CroydonAlert area85None
Shuttle and CrayAlert area48None

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 Bromley are in radon Affected Areas, up to the 5–10% 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).

TQ3370: Under 1% of homes above the action levelTQ3371: Under 1% of homes above the action levelTQ3468: Under 1% of homes above the action levelTQ3469: Under 1% of homes above the action levelTQ3470: Under 1% of homes above the action levelTQ3471: Under 1% of homes above the action levelTQ3567: Under 1% of homes above the action levelTQ3568: Under 1% of homes above the action levelTQ3569: Under 1% of homes above the action levelTQ3570: Under 1% of homes above the action levelTQ3571: Under 1% of homes above the action levelTQ3666: Under 1% of homes above the action levelTQ3667: Under 1% of homes above the action levelTQ3668: Under 1% of homes above the action levelTQ3669: Under 1% of homes above the action levelTQ3670: Under 1% of homes above the action levelTQ3671: Under 1% of homes above the action levelTQ3764: 3–5% of homes above the action levelTQ3765: Under 1% of homes above the action levelTQ3766: Under 1% of homes above the action levelTQ3767: Under 1% of homes above the action levelTQ3768: Under 1% of homes above the action levelTQ3769: Under 1% of homes above the action levelTQ3770: Under 1% of homes above the action levelTQ3771: Under 1% of homes above the action levelTQ3864: 3–5% of homes above the action levelTQ3865: 3–5% of homes above the action levelTQ3866: Under 1% of homes above the action levelTQ3867: Under 1% of homes above the action levelTQ3868: Under 1% of homes above the action levelTQ3869: 1–3% of homes above the action levelTQ3870: 1–3% of homes above the action levelTQ3961: 3–5% of homes above the action levelTQ3962: 3–5% of homes above the action levelTQ3964: 3–5% of homes above the action levelTQ3965: 3–5% of homes above the action levelTQ3966: Under 1% of homes above the action levelTQ3967: Under 1% of homes above the action levelTQ3968: Under 1% of homes above the action levelTQ3969: 1–3% of homes above the action levelTQ3970: 1–3% of homes above the action levelTQ3971: Under 1% of homes above the action levelTQ4057: 3–5% of homes above the action levelTQ4058: 3–5% of homes above the action levelTQ4059: 3–5% of homes above the action levelTQ4060: 3–5% of homes above the action levelTQ4061: 3–5% of homes above the action levelTQ4062: 3–5% of homes above the action levelTQ4063: 3–5% of homes above the action levelTQ4064: 3–5% of homes above the action levelTQ4065: Under 1% of homes above the action levelTQ4066: Under 1% of homes above the action levelTQ4067: Under 1% of homes above the action levelTQ4068: Under 1% of homes above the action levelTQ4069: Under 1% of homes above the action levelTQ4070: Under 1% of homes above the action levelTQ4071: Under 1% of homes above the action levelTQ4073: Under 1% of homes above the action levelTQ4157: 3–5% of homes above the action levelTQ4158: 3–5% of homes above the action levelTQ4159: 3–5% of homes above the action levelTQ4160: 5–10% of homes above the action levelTQ4161: 5–10% of homes above the action levelTQ4162: 5–10% of homes above the action levelTQ4163: 5–10% of homes above the action levelTQ4164: 1–3% of homes above the action levelTQ4165: Under 1% of homes above the action levelTQ4166: Under 1% of homes above the action levelTQ4167: Under 1% of homes above the action levelTQ4168: Under 1% of homes above the action levelTQ4169: Under 1% of homes above the action levelTQ4170: 1–3% of homes above the action levelTQ4171: Under 1% of homes above the action levelTQ4172: Under 1% of homes above the action levelTQ4173: Under 1% of homes above the action levelTQ4257: 5–10% of homes above the action levelTQ4258: 5–10% of homes above the action levelTQ4259: 5–10% of homes above the action levelTQ4260: 5–10% of homes above the action levelTQ4261: 5–10% of homes above the action levelTQ4262: 5–10% of homes above the action levelTQ4263: 3–5% of homes above the action levelTQ4264: 1–3% of homes above the action levelTQ4265: Under 1% of homes above the action levelTQ4266: Under 1% of homes above the action levelTQ4267: Under 1% of homes above the action levelTQ4268: Under 1% of homes above the action levelTQ4269: 1–3% of homes above the action levelTQ4270: 1–3% of homes above the action levelTQ4271: Under 1% of homes above the action levelTQ4272: Under 1% of homes above the action levelTQ4273: Under 1% of homes above the action levelTQ4356: 3–5% of homes above the action levelTQ4357: 5–10% of homes above the action levelTQ4358: 5–10% of homes above the action levelTQ4359: 5–10% of homes above the action levelTQ4360: 5–10% of homes above the action levelTQ4361: 5–10% of homes above the action levelTQ4362: 5–10% of homes above the action levelTQ4364: 1–3% of homes above the action levelTQ4365: Under 1% of homes above the action levelTQ4366: Under 1% of homes above the action levelTQ4367: Under 1% of homes above the action levelTQ4368: Under 1% of homes above the action levelTQ4369: 1–3% of homes above the action levelTQ4370: 1–3% of homes above the action levelTQ4371: Under 1% of homes above the action levelTQ4457: 5–10% of homes above the action levelTQ4458: 5–10% of homes above the action levelTQ4459: 3–5% of homes above the action levelTQ4460: 3–5% of homes above the action levelTQ4461: 3–5% of homes above the action levelTQ4462: 3–5% of homes above the action levelTQ4463: 3–5% of homes above the action levelTQ4464: 3–5% of homes above the action levelTQ4465: 1–3% of homes above the action levelTQ4466: Under 1% of homes above the action levelTQ4467: Under 1% of homes above the action levelTQ4468: Under 1% of homes above the action levelTQ4469: 1–3% of homes above the action levelTQ4470: Under 1% of homes above the action levelTQ4471: Under 1% of homes above the action levelTQ4472: Under 1% of homes above the action levelTQ4556: 3–5% of homes above the action levelTQ4557: 3–5% of homes above the action levelTQ4558: 3–5% of homes above the action levelTQ4561: 3–5% of homes above the action levelTQ4562: 3–5% of homes above the action levelTQ4563: 3–5% of homes above the action levelTQ4564: 3–5% of homes above the action levelTQ4565: 1–3% of homes above the action levelTQ4566: 1–3% of homes above the action levelTQ4567: 1–3% of homes above the action levelTQ4568: 1–3% of homes above the action levelTQ4569: 1–3% of homes above the action levelTQ4570: Under 1% of homes above the action levelTQ4571: Under 1% of homes above the action levelTQ4661: 3–5% of homes above the action levelTQ4662: 3–5% of homes above the action levelTQ4663: 3–5% of homes above the action levelTQ4664: 3–5% of homes above the action levelTQ4665: 1–3% of homes above the action levelTQ4666: 1–3% of homes above the action levelTQ4667: 1–3% of homes above the action levelTQ4668: 1–3% of homes above the action levelTQ4669: 1–3% of homes above the action levelTQ4670: 1–3% of homes above the action levelTQ4761: 3–5% of homes above the action levelTQ4762: 3–5% of homes above the action levelTQ4763: 3–5% of homes above the action levelTQ4764: 3–5% of homes above the action levelTQ4765: 1–3% of homes above the action levelTQ4766: 1–3% of homes above the action levelTQ4767: 1–3% of homes above the action levelTQ4768: 1–3% of homes above the action levelTQ4769: 1–3% of homes above the action levelTQ4770: 1–3% of homes above the action levelTQ4865: 1–3% of homes above the action levelTQ4866: 3–5% of homes above the action levelTQ4868: 3–5% of homes above the action level© OpenStreetMap contributors · BGS/UKHSA
Under 1%1–3%3–5%5–10%
Share of the borough’s area in each band
Under 1% of homes52%
1–3% of homes28%
3–5% of homes14%
5–10% of homes6%

48% of Bromley’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 borough.

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 Bromley

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

ABCD
TownPeopleHigh or mediumLowHazard
Bromley325,4692%0.6%C−
Lewisham300,7643.6%1.4%D
Croydon389,2421.9%0.9%C−
Greenwich288,1172%0.9%C−
Crockenhill1,5690%0%A
Swanley17,2090%0%A
Joyden's Wood4,9120%0%A
Bexley246,0740.6%1%C+

Lewisham, 4.7 miles north-west, has the most homes at risk around Bromley (3.6% at high or medium). Crockenhill, Swanley and Joyden's Wood have none.

Be ready

Get ready for what Bromley 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.
  • Bromley’s warning areas include Groundwater flooding in South East London and Ravensbourne at Bromley.
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 Bromley
  • 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 Bromley

Does Bromley flood?

The last flood the Environment Agency recorded inside the borough was in August 1977. 2% 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 6.9% of homes are at high or medium risk from surface water, when heavy rain overwhelms the drains. Bromley grades C− for hazard risk against UK towns.

Which parts of Bromley are at risk of flooding?

From rivers and the sea, the places the Environment Agency warns directly: Kyd Brook at Petts Wood, Chaffinch Brook and St James Stream at Elmers End, River Quaggy at Chinbrook, Mottingham and Eltham and River Cray in St Marys Cray, Sidcup, Bexley and Crayford. Surface water can collect in low spots anywhere in the borough. Check a specific address on GOV.UK’s long-term flood risk service.

When did Bromley last flood?

The recorded flood outlines inside the borough run from 1965 to 1977 (3 years); the largest was in 1968. Flood warnings have been issued for parts of the borough since 2006, most recently on 27 September 2024.

Is Bromley at risk of surface water flooding?

About 3.6% of homes are at high risk and 3.3% at medium risk from surface water, against 2% 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 Bromley?

48% of the borough’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 Bromley now?

No flood warning or alert was in force near Bromley at 6 November 2026, 04:12. 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.