FloodRadar
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Grantham, Lincolnshire
Up to Medium likelihood
Properties in NG31 9BF sit in the Environment Agency's Medium 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% | 0 | 0 |
| Medium | 1% – 3.3% | 1 | 1 |
| Low | 0.1% – 1% | 31 | 31 |
| Very low | below 0.1% | 0 | 0 |
Over a 25-year mortgage, a property in a medium-likelihood area has a 22–57% chance of flooding at least once.
The ground here sits at about 53 m above sea level and falls 45 m across the surrounding 800 m. Surface water reaching this point runs off ground lying to the north-east, 4.3 m higher.
Because properties in the medium likelihood band; 2 recorded floods nearby; 146 official warnings since 2006.
The map above shows the real EA rivers & sea likelihood cells around NG31 9BF. 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 | Recorded flood | Approx. distance |
|---|---|---|
| Jan 2025 | LNA_2025_01_Fluvial_Grantham | ~0.4 km |
| Jan 1922 | LNA_1922_08_Grantham | ~1.0 km |
EA Recorded Flood Outlines — absence of a record never proves a place has not flooded. The full report tests whether any extent covered the exact spot.
2007 UK floods (2007, 9 warnings nearby) · 2013-14 UK winter floods (2013, 5 warnings nearby) · Babet (2023, 4 warnings nearby) · Dylan (2017, 2 warnings nearby)
| Gauge | River | Distance | Typical high | Highest on record |
|---|---|---|---|---|
| Saltersford | River Witham | 1.6 km | 0.74 m | 1.54 m |
| SALTERSFORD RAINGAUGE WITS | — | 1.7 km | — | — |
| CRINGLE BROOK GS GREAT PONTON | — | 5.4 km | — | — |
| Allington | Foston Beck | 6.8 km | 0.85 m | 1.83 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 |
|---|---|---|---|---|
| Grantham - Bridge End Grove Cso | River Witham | 0.6 km | 2 (2024) | 0 |
| Alma Park Stw - Sso | Unknown Trib. | 2.8 km | 1 (2024) | 8 |
| Manthorpe Mill Pumping Station | Running Furrows Drain | 3.2 km | 61 (2024) | 105 |
| Harlaxton Water Recycling Centre | Trib Of Grantham Canal | 3.5 km | 51 (2024) | 352 |
Official annual EDM figures — a water-quality signal for local watercourses, not a property flood-risk factor.
27 mapped flood-defence assets within 500 m — nearest ~29 m (natural high ground, engineered high ground, wall). 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 NG31 9BF — all in the NG31 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. 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 NG31 district.