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Up to High likelihood
Properties in SY21 8DG 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% | 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.
SY21 8DG gets about 805 mm of rain a year on average (wettest month December, 82 mm; driest February, 54 mm). That is 31% 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), 2.1 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 113 m above sea level and falls 57 m across the surrounding 800 m. Surface water reaching this point runs off ground lying to the west-north-west, 41.0 m higher.
The nearest watercourse on the river map is Pwll Trewern, about 30 m from the centre of SY21 8DG. It flows into Afon Hafren (River Severn) about 6.8 km downstream.
A gauge downstream shows water that has already passed this point; one upstream sees it first. Distances along the river are from the point on Pwll Trewern nearest the centre of SY21 8DG. From Ordnance Survey’s river map (OS Open Rivers), which leaves out small streams, ditches and culverts, so a nearer one may exist. This describes where water goes on the map; it says nothing about flooding at any address. Contains OS data © Crown copyright and database rights 2026.
Because properties in the high likelihood band; 622 official warnings since 2006.
The map above shows the real EA rivers & sea likelihood cells around SY21 8DG. 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.
Counted from the warning records of the Environment Agency and Natural Resources Wales; the Environment Agency's record covers England only. Warnings cover flood areas, not individual addresses.
The Environment Agency's Recorded Flood Outlines cover England only, so there is no mapped flood record here to be empty — this is an absence of coverage, not an absence of floods. Recorded flooding here is mapped by Natural Resources Wales.
2013-14 UK winter floods (2013, 19 warnings nearby) ▶ replay it here · Henk (2024, 7 warnings nearby) ▶ replay it here · 2007 UK floods (2007, 7 warnings nearby) ▶ replay it here · Dennis (2020, 5 warnings nearby) ▶ replay it here
| Gauge | River | Distance | Typical high | Highest on record |
|---|---|---|---|---|
| Crew Green | River Severn | 4.5 km | 5.20 m | 6.58 m |
| Llandrinio River Station | Severn | 4.9 km | 5.67 m | — |
| Hayes Basin | Field Drain | 6.0 km | 1.00 m | 4.23 m |
| Cae Howel | New Cut | 6.4 km | 3.40 m | 6.27 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 |
|---|---|---|---|---|
| Trewern Wastewater Treatment Works | — | 3.8 km | — | — |
Official annual EDM figures — a water-quality signal for local watercourses, not a property flood-risk factor.
The Environment Agency's register of mapped flood-defence assets covers England only, so it holds nothing here — that is the reach of the register, not an absence of defences. Defences here are held by Natural Resources Wales. 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.
Flooded here before? Log it and see what your floods had in common.
At-risk postcodes near SY21 8DG — all in the SY21 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 SY21 district.