Does HP1 flood?

Yes — parts of the HP1 district carry real flood risk: 7 of its 14 at-risk postcodes reach the Environment Agency's High likelihood band. The HP1 postcode district covers Bovingdon, Flaunden and Chipperfield, Boxmoor, Chaulden and Warners End, close to Hemel Hempstead, Redbourn, Chesham, and surrounding villages in parts of Hertfordshire and Buckinghamshire.

14 postcodes in the HP1 district appear in the Environment Agency's rivers-and-sea flood-risk dataset — worst bands: 7 high, 2 medium, 5 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 HP1 postcodes are at risk?

HP1 1NA up to High HP1 1NE up to High HP1 2BL up to High HP1 2RJ up to High HP1 2RL up to High HP1 2RX up to High HP1 2RZ up to High HP1 1DH up to Medium HP1 1LS up to Medium HP1 1BS up to Low HP1 1BZ up to Low HP1 2BN up to Low HP1 3AQ up to Low HP1 3BB up to Low

Rivers and flooding history near HP1

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

Hemel Hempstead, Old Fishery Lane on the River Bulbourne — 0.7 km away, highest on record 1.80m
Gadebridge Park on the River Gade — 1.5 km away, highest on record 0.41m
Hemel Hempstead, Two Waters Road on the River Bulbourne — 1.8 km away, highest on record 1.19m
Chesham on the River Chess — 9.8 km away, highest on record 0.88m

22 official flood warnings and alerts have been raised within ~10 km of the district's centre since 2006 (2 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):

January 2021 flooding — about 2.4 km from the centre
January 2021 flooding — about 2.4 km from the centre
EA06OctoberAutumn2020 (2020) — about 1.7 km from the centre
September 2016 flooding — about 2.2 km from the centre

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

🏠 Buying or renting in HP1? 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

HP3 HP4 HP5 HP7 HP8 HP10 HP11 HP12

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.