Does AL5 flood?

Yes — parts of the AL5 district carry real flood risk: 3 of its 12 at-risk postcodes reach the Environment Agency's High likelihood band. The AL5 postcode district sits close to Harpenden, Upper Lee, Redbourn and surrounding villages in parts of Hertfordshire and Luton.

12 postcodes in the AL5 district appear in the Environment Agency's rivers-and-sea flood-risk dataset — worst bands: 3 high, 4 low, 5 very low. A postcode not listed here has no properties in any recorded risk band (which is good news, but never proof it cannot flood).

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Which AL5 postcodes are at risk?

AL5 4UN up to High AL5 5FE up to High AL5 5UN up to High AL5 4NH up to Low AL5 5AE up to Low AL5 5BX up to Low AL5 5BZ up to Low AL5 4NQ up to Very low AL5 4UU up to Very low AL5 5EF up to Very low AL5 5EG up to Very low AL5 5EP up to Very low

Rivers and flooding history near AL5

The rivers that matter here, each monitored live on FloodRadar:

Harpenden on the River Lee — 0.7 km away, highest on record 1.69m
Luton East Hyde on the River Lee — 3.7 km away, highest on record 2.77m
Whitwell on the River Mimram — 7 km away, highest on record 0.28m
Fulling Mill on the River Mimram — 8.4 km away, highest on record 0.55m

28 official flood warnings and alerts have been raised within ~10 km of the district's centre since 2006 (1 at warning level or above), most recently 19 December 2024. Warnings cover flood areas, not individual addresses.

Recorded flood extents near the district (Environment Agency record):

EA06SeptemberAutumn2024 (2024) — about 3.4 km from the centre
Winter 2013/2014 (2013) — about 47.8 km from the centre
May 2007 flooding — about 0.4 km from the centre
Mayspring 2007 flooding — about 3.2 km from the centre

Records, not floods: no outline on the record is not evidence a place has not flooded.

🏠 Buying or renting in AL5? The full property flood-risk report covers any postcode here — the official likelihood band, every recorded flood nearby with distances, warning history year by year, how the local rivers behave, and an insurance outlook, print-ready for £19. See what's in the report →

Flood risk in nearby postcode districts

AL4 AL6 AL3 AL2 AL8 AL1 AL9 AL10

Band = the worst likelihood band of any property in that postcode (EA Risk of Flooding from Rivers & Sea, defence-adjusted, area-level). Check any postcode in detail — or get the full £19 property report — at the property flood-risk report. © Environment Agency copyright and/or database right 2025. All rights reserved. Some features of this map are based on digital spatial data from the Centre for Ecology & Hydrology, © NERC (CEH). © Crown Copyright and Database Rights 2025 OS AC0000807064. This product is produced in part from PAF® and Multiple Residence Data, the copyright in which is owned by Royal Mail Group Limited and/or Royal Mail Group plc. All rights reserved. Licence number AC0000807064.