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Aintree Sefton Arms station geograph-2387124-by-Ben-BrooksbankPhoto: Ben Brooksbank · CC BY-SA 2.0
AHazard risk Grade
Flood & hazards in Aintree · Environment Agency

None of Aintree’s homes are at high or medium risk from rivers or the sea; 30% are from surface water

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. Aintree’s Hazard risk Grade is A: #1 of 25 in Merseyside.

0warnings in force0%at low risk
In brief

What stands out about Aintree’s hazards

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

Rain, not the river30% of homes sit where heavy rain can flood the streets; none are at risk from rivers or the sea.The River Alt ran its 4th-highest in January 20252.11 m at Kirkby on 1 January 2025, 12 cm under the record set in 2004.Low radonEvery 1 km square over Aintree is in the lowest radon band: under 1% of homes above the action level.
By hazard

What Aintree faces

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

Rivers and the sea

0%of homes at high or medium risk
None at high or medium risk
0 homes by the EA’s own count

Surface water

30%of homes at high or medium risk
More than 99% of UK towns
About 820 households

The River Alt

1.24 mhighest in winter 2025–26 at Kirkby
31st-highest of 35 winters
Record 2.22 m, August 2004

Flood warnings

0flood warnings since 2006
64 flood alerts for the wider area
Never warned

Radon

0%of the town in a radon Affected Area
Highest band here: Under 1% 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

Aintree grades A for hazard risk

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

Homes at high or medium flood risk (0%)Fewer than 86% 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 Aintree

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.

© OpenStreetMap contributors · EA NaFRA2
HighMediumLowrivers & seaHighMediumLowsurface waterAintree’s built-up area

No home in Aintree is in the high or medium band for rivers or the sea. Surface-water risk is spread across the town, in dips, underpasses and along small streams, which is why more homes are exposed to it.

Rivers and the sea

0% of Aintree’s homes are at high or medium risk from rivers or the sea

The Environment Agency’s national map, allowing for defences. None are in the low-risk band.

High risk0%of homes · 1 in 30 a year or more0 homes, EA count
Medium risk0%of homes · 1 in 30 to 1 in 1000 homes, EA count
Low risk0%of homes · 1 in 100 to 1 in 1,0000 homes, EA count
Where Aintree sits among 3,735 UK towns
35%NoneAintree
23%Under 0.5%
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.

Towns its size: 92nd of 709 from the fewest homes at risk
#TownPeopleHigh or med.
1Banstead Surrey8,9290%
2Warlingham Surrey8,9180%
3Whitnash Warwickshire8,9140%
…
90Selston Nottinghamshire6,2780%
91Burghfield Common Berkshire6,2160%
92Aintree Merseyside6,2120%
93Throckley Tyne and Wear6,2070%
94Annesley Woodhouse Nottinghamshire6,1620%
…
708Howden East Riding of Yorkshire4,57262%
709Stainforth South Yorkshire5,99963%

UK towns of 4,000 to 9,000 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

30% of Aintree’s homes are at high or medium risk from surface water

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 water30%
Rivers and the sea0%
0%21%42% of homes

About 23% of homes are at high risk of surface-water flooding (a 1 in 30 chance or more each year) and 6.3% at medium risk: roughly 820 households. A further 12% face a low risk from surface water. That is more than 99% of UK towns.

~820
households at high or medium risk
12%
of homes at low risk
99%
of UK towns have a smaller share
2,992
addresses read on the map

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.

River levels

The River Alt in January 2025 rose to its 4th-highest level since 1990

The highest level each winter (October to September) at the Environment Agency’s Kirkby gauge, since 1990. The river normally runs between 0.21 m and 1.30 m here.

Highest level each winter, metres
Winter 1990–91: highest 1.33 m · 1 days above the normal rangeWinter 1991–92: highest 1.22 m · 0 days above the normal rangeWinter 1992–93: highest 1.63 m · 4 days above the normal rangeWinter 1993–94: highest 1.27 m · 0 days above the normal rangeWinter 1994–95: highest 1.74 m · 5 days above the normal rangeWinter 1995–96: highest 0.97 m · 0 days above the normal rangeWinter 1996–97: highest 1.18 m · 0 days above the normal rangeWinter 1997–98: highest 1.42 m · 3 days above the normal rangeWinter 1998–99: highest 1.43 m · 1 days above the normal rangeWinter 1999–00: highest 1.52 m · 4 days above the normal rangeWinter 2000–01: highest 1.91 m on 30 October 2000 · 10 days above the normal rangeWinter 2001–02: highest 1.91 m on 9 September 2002 · 3 days above the normal rangeWinter 2002–03: highest 1.61 m · 2 days above the normal rangeWinter 2003–04: highest 2.22 m on 10 August 2004 · 4 days above the normal rangeWinter 2004–05: highest 1.82 m · 3 days above the normal rangeWinter 2005–06: highest 1.48 m · 3 days above the normal rangeWinter 2006–07: highest 1.51 m · 5 days above the normal rangeWinter 2007–08: highest 1.78 m · 11 days above the normal rangeWinter 2008–09: highest 1.70 m · 4 days above the normal rangeWinter 2009–10: highest 2.16 m on 20 July 2010 · 3 days above the normal rangeWinter 2010–11: highest 1.46 m · 1 days above the normal rangeWinter 2011–12: highest 2.01 m on 24 September 2012 · 5 days above the normal rangeWinter 2012–13: highest 1.57 m · 3 days above the normal rangeWinter 2013–14: highest 0.97 m · 0 days above the normal rangeWinter 2014–15: highest 1.30 m · 1 days above the normal rangeWinter 2015–16: highest 1.82 m · 2 days above the normal rangeWinter 2016–17: highest 1.37 m · 1 days above the normal rangeWinter 2017–18: highest 1.44 m · 1 days above the normal rangeWinter 2018–19: highest 1.83 m on 24 September 2019 · 6 days above the normal rangeWinter 2019–20: highest 1.73 m · 8 days above the normal rangeWinter 2020–21: highest 2.20 m on 20 January 2021 · 13 days above the normal rangeWinter 2021–22: highest 1.53 m · 7 days above the normal rangeWinter 2023–24: highest 1.76 m · 7 days above the normal rangeWinter 2024–25: highest 2.11 m on 1 January 2025 · 6 days above the normal rangeWinter 2025–26: highest 1.24 m · 0 days above the normal range’03–04’20–21’09–10Record 2.22 m, 2004Top of normal range
1990–912025–26
The highest days on record
  • 10 August 20042.22 m
  • 20 January 20212.20 m
  • 20 July 20102.16 m
  • 1 January 20252.11 m
  • 24 September 20122.01 m
  • 30 October 20001.91 m

The River Alt has topped its normal range on 127 days since 1990, most in the winters of 2020–21 and 2007–08. By its highest day, the winter of 2025–26 was the 31st-highest of the 35.

Environment Agency Hydrology API, Kirkby (station 694744), 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 Aintree · 0 warnings in 20 years

The Environment Agency has 0 flood warning areas and 1 alert area reaching into the town; warnings since the service began in 2006.

Now: no flood warnings or alerts for Aintree (checked 4 November 2026, 05:01). Check for flooding on GOV.UK →
Warnings and alerts each year for areas in Aintree
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)
Show the 1 warning and alert areas
AreaKindSince 2006Now
River Alt, Formby to HuytonAlert area64None

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

Aintree 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).

SJ3697: Under 1% of homes above the action levelSJ3698: Under 1% of homes above the action levelSJ3699: Under 1% of homes above the action levelSJ3798: Under 1% of homes above the action levelSJ3799: Under 1% of homes above the action levelSJ3898: Under 1% of homes above the action levelSJ3899: Under 1% of homes above the action level© OpenStreetMap contributors · BGS/UKHSA
Under 1%
Share of the town’s area in each band
Under 1% of homes100%

Every 1 km square over Aintree 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.

Neighbours

Flood risk in the places around Aintree

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

Maghull: Hazard risk C−Bootle: Hazard risk AKirkby: Hazard risk BLitherland: Hazard risk ALydiate: Hazard risk B+Crosby: Hazard risk AKnowsley: Hazard risk C−MaghullBootleKirkbyLitherlandLydiateCrosbyKnowsleyAintree
ABCD
TownPeopleHigh or mediumLowHazard
Aintree6,2120%0%A
Maghull20,3671.9%3.2%C−
Bootle53,7220%0%A
Kirkby45,559under 0.1%0.3%B
Litherland18,7520%0%A
Lydiate6,5160%under 0.1%B+
Crosby50,2180%0%A
Knowsley2,3453%1.1%C−

Knowsley, 4.2 miles south-east, has the most homes at risk around Aintree (3% at high or medium).

Be ready

Get ready for what Aintree 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.
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.
When the river rises
  • 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.
Before you buy or rent in Aintree
  • 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.
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.
  • 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 Aintree

Does Aintree flood?

0% 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 30% of homes are at high or medium risk from surface water, when heavy rain overwhelms the drains. Aintree grades A for hazard risk against UK towns.

Is Aintree at risk of surface water flooding?

About 23% of homes are at high risk and 6.3% at medium risk from surface water, against 0% 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 Aintree?

Not by the atlas: every 1 km square over Aintree 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 Aintree now?

No flood warning or alert was in force near Aintree at 4 November 2026, 05:01. 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 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.