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Up to High likelihood
Properties in SO45 1TW 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% | 1 | 0 |
| Medium | 1% – 3.3% | 4 | 0 |
| Low | 0.1% – 1% | 1 | 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.
SO45 1TW gets about 814 mm of rain a year on average (wettest month November, 100 mm; driest May, 46 mm). That is 30% 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), 0.2 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 -8 m above sea level and falls 34 m across the surrounding 800 m. Surface water reaching this point runs off ground lying to the west-south-west, 21.2 m higher.
The river map has no watercourse within 1 km of the centre of SO45 1TW.
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; 310 official warnings since 2006.
The map above shows the real EA rivers & sea likelihood cells around SO45 1TW. 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.
None mapped within ~1 km of this postcode's centre.
No recorded outline near this postcode means no flood was mapped here, which is not evidence none happened: the Environment Agency mapped only some floods, mapping effort rose sharply after about 2000, and surface-water flooding is largely absent from this record. The full report tests every other flood source at the exact building.
2013-14 UK winter floods (2013, 52 warnings nearby) ▶ replay it here · Barra (2021, 6 warnings nearby) ▶ replay it here · Eunice (2022, 6 warnings nearby) ▶ replay it here · Ashley (2024, 5 warnings nearby) ▶ replay it here
| Gauge | River | Distance | Typical high | Highest on record |
|---|---|---|---|---|
| Brownwich Pond | Brownwich Stream | 4.7 km | 1.18 m | 1.18 m |
| Titchfield Canal | River Meon | 7.7 km | 2.80 m | 2.80 m |
| Titchfield | River Meon | 7.7 km | 2.00 m | 2.35 m |
| Hobb Lane | River Hamble | 10.9 km | 20.80 m | 21.96 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 |
|---|---|---|---|---|
| Ashlett Creek Wwtw | Southampton Water | 1.4 km | 32 (2024) | 516 |
| West Common Road Fawley Ceo | Dark Water | 3.3 km | 28 (2024) | 84 |
| West Common Road Fawley Ceo | Dark Water | 3.3 km | 1 (2024) | 0 |
| Hook Park Wps | Southampton Water | 3.3 km | 14 (2024) | 80 |
Official annual EDM figures — a water-quality signal for local watercourses, not a property flood-risk factor.
No mapped flood-defence assets within 500 m of the postcode centre. 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 SO45 1TW — all in the SO45 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. 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 SO45 district.