FloodRadar
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Boundstone, Surrey
Up to High likelihood
Properties in GU10 4NX sit in the Environment Agency's High flood-likelihood band (worst property). The band is the worst found in the postcode — it describes the land around properties (defence-adjusted, rivers & sea), not any single address, and not today's conditions.
| Likelihood band | Annual chance | Properties | Of which homes |
|---|---|---|---|
| High | greater than 3.3% | 2 | 2 |
| Medium | 1% – 3.3% | 0 | 0 |
| Low | 0.1% – 1% | 0 | 0 |
| Very low | below 0.1% | 0 | 0 |
Over a 25-year mortgage, a property in a high-likelihood area has at least a 57% chance of flooding at least once.
GU10 4NX gets about 823 mm of rain a year on average (wettest month November, 98 mm; driest May, 50 mm). That is 29% drier than the UK as a whole, which averages 1,163 mm a year.
A thirty-year average for the surrounding area, not a measurement at this address and not a flood risk on its own: a dry area floods when a storm sits over it, and a wet one may drain away perfectly well. Source: Met Office HadUK-Grid 1991–2020 (5 km grid), 2.0 km away. Average rainfall: HadUK-Grid v1.3.2, Met Office. Contains public sector information licensed under the Open Government Licence v3.0.
The ground here sits at about 83 m above sea level and falls 39 m across the surrounding 800 m. Surface water reaching this point runs off ground lying to the south-south-east, 24.2 m higher.
The river map has no watercourse within 1 km of the centre of GU10 4NX.
That means this spot is not on the river map, not that there is no water here: Ordnance Survey’s river map (OS Open Rivers) leaves out small streams, ditches and culverts. Contains OS data © Crown copyright and database rights 2026.
Because properties in the high likelihood band; 2 recorded flood outlines mapped nearby; 151 official warnings since 2006.
The map above shows the real EA rivers & sea likelihood cells around GU10 4NX. The small panels are illustrative previews of the report's per-layer map views — the full report draws each layer for real, plus recorded extents, defences and a building picker on an interactive map.
Warnings cover flood areas, not individual addresses.
| Date | Mapped flood extent | Approx. distance |
|---|---|---|
| Jan 1990 | 06FebruaryWinter1990 | ~1.4 km |
| Jan 1968 | 06SeptemberAutumn1968 | ~1.7 km |
These are extents the Environment Agency has mapped, not a list of every flood. Records, not floods: no outline on the record is not evidence a place has not flooded. The full report tests whether any extent covered the exact spot.
2013-14 UK winter floods (2013, 13 warnings nearby) ▶ replay it here · Dennis (2020, 4 warnings nearby) ▶ replay it here · Herminia (2025, 3 warnings nearby) ▶ replay it here · Henk (2024, 3 warnings nearby) ▶ replay it here
| Gauge | River | Distance | Typical high | Highest on record |
|---|---|---|---|---|
| Tilford | River Wey | 4.4 km | 1.40 m | 2.09 m |
| Crondall Pond | River Hart | 5.8 km | 0.80 m | 1.19 m |
| Crondall Bridge | River Hart | 6.0 km | 0.49 m | 1.12 m |
| Tongham | River Blackwater | 7.2 km | 1.50 m | 1.79 m |
Live levels, predictions and rain-response behaviour are on each gauge's page and in the property report.
| Overflow | Discharges into | Distance | Spills | Hours |
|---|---|---|---|---|
| Waverley Lane Sps | Farnham Bourne | 3.3 km | 11 (2024) | 70 |
| Farnham | Farnham Park Tributary | 3.7 km | 52 (2024) | 529 |
| Bentley Wastewater Treatment Works | River Wey And Groundwater | 4.2 km | 62 (2024) | 706 |
Official annual EDM figures — a water-quality signal for local watercourses, not a property flood-risk factor.
6 mapped flood-defence assets within 500 m — nearest ~35 m (natural high ground). Defences reduce risk, never remove it.
The interactive flood-risk map with a building picker (your exact house, not the postcode), the 2050s climate view, surface-water and planning flood zones at your building, exact recorded-flood distances, year-by-year warning charts, watercourses including culverted streams, an insurance outlook with the Flood Re rules, and a printable document with every dataset receipt — start with the free preview, unlock for £19.
At-risk postcodes near GU10 4NX — all in the GU10 district.
© 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. Place names: Contains OS data © Crown copyright and database rights 2026. Contains Royal Mail data © Royal Mail copyright and database right 2026. Contains National Statistics data © Crown copyright and database right 2026. Licensed under the Open Government Licence v3.0. Recorded Flood Outlines and warning history © Environment Agency copyright and/or database right 2025. Storm-overflow figures: EA Event Duration Monitoring (England); live overflow status © the water companies, incl. Dŵr Cymru Welsh Water and Scottish Water. Flood defences © Environment Agency (OGL v3). This page summarises public area-level data — it is not a flood-risk survey and not a substitute for the official GOV.UK service. All data sources & licences. More postcodes: the GU10 district.