What it does
Enter a postcode or address and the checker finds the postcode’s location, then looks up the Environment Agency flood zones at and around it. It tells you whether the area is in Flood Zone 1 (low probability), 2 (medium) or 3 (high) of flooding from rivers and the sea, and warns you when a higher zone starts close enough that it may cover your property.
The postcode check is free with no account. It’s meant as a first check for buyers, homeowners, landlords and anyone planning building work.
What the flood zones are
Flood zones come from the Environment Agency’s Flood Map for Planning, which councils use to decide where new building can go and when a flood risk assessment is needed. The zones show the chance of flooding from rivers and the sea in any year, as if there were no flood defences.
Where the data comes from
The flood and postcode data is public and published under the Open Government Licence. Typed addresses are matched to a postcode using Mapbox.
- Flood Zones 2 and 3
- Environment Agency Flood Map for Planning, via planning.data.gov.uk (flood-risk-zone dataset)
- Addresses and postcodes
- Postcodes.io (ONS and Ordnance Survey open data)
planning.data.gov.uk republishes the Environment Agency’s map, so after an update there can be a short delay before it reaches this checker. The Environment Agency’s own map is always the final word.
What it can’t see
Flood zones don’t cover surface water flooding from heavy rain, groundwater or reservoirs — check those on the government’s long-term flood risk service. The check also works from a postcode’s centre rather than the outline of your building, and it can’t tell you whether a particular house has flooded before.
Guidance only — not an official flood risk assessment. Built from the Environment Agency's Flood Map for Planning via planning.data.gov.uk, which shows river and sea flooding only and ignores flood defences. Check surface water risk separately, and confirm with the Environment Agency or a flood risk specialist before you buy, build or insure.
Contact
Questions, corrections or data problems: hello@floodchecker.co.uk. Flood Checker is a sister site of TPO Checker, which checks Tree Preservation Orders. See our privacy policy for how searches are handled.