Is your home at risk of flooding?

Flood Zone 3 is the Environment Agency’s highest flood zone: land with a 1% (1 in 100) or greater chance of flooding from rivers in any year, or a 0.5% (1 in 200) or greater chance of flooding from the sea. Flood Zone 2 is medium probability (between 0.1% and 1% from rivers, or 0.1% and 0.5% from the sea), and Flood Zone 1 is everywhere else — less than a 0.1% (1 in 1,000) chance.

Yes. The postcode check is free with no sign-up: enter a postcode in England and you’ll see its planning flood zone – flooding from rivers and the sea – straight away. Surface water, reservoirs, past floods and flood defences are in the full property report, which you only pay for if you want it.

It can. Insurers use their own flood models rather than the planning flood zones directly, but homes in Flood Zones 2 and 3 are more likely to face higher premiums or excesses. Flood Re, a scheme run with the insurance industry, helps keep cover affordable for most homes built before 2009. Homes built from 2009 onwards, and businesses, aren’t covered by it.

Usually, yes. Lenders mainly want to know the property can be insured, so they may ask for proof of buildings insurance and look at whether it has flooded before. If you’re buying, get an insurance quote early, ask the seller about past flooding, and tell your conveyancer — an environmental search will cover flood risk in more detail.

Flood Re is a reinsurance scheme set up by the government and insurers so that homes at high flood risk can still get affordable cover. You don’t apply to it — your insurer uses it behind the scenes. It covers most homes built before 1 January 2009 and is due to run until 2039.

If the property is in Flood Zone 2 or 3, a planning application — including for most householder extensions — needs a flood risk assessment. For small extensions it can be short, following the Environment Agency’s standing advice. In Flood Zone 1 you only need one for sites of 1 hectare or more, or where other flood risks have been identified.

Flood zones themselves only cover rivers and the sea. Surface water flooding — heavy rain that can’t drain away — is mapped separately by the Environment Agency, and affects more properties in England than rivers and the sea do. The free check shows the flood zone only. The full property report adds the Environment Agency’s surface water risk at and around the postcode, with a street-level map, and you can also check the government’s long-term flood risk service.

No. The Flood Map for Planning shows the risk as if there were no defences, because defences can be overtopped or fail and planning decisions last for decades. A property behind a good defence can still be in Flood Zone 3. The long-term flood risk service does account for defences, so the two can give different answers.

No — England only. Flood maps elsewhere in the UK are published by Natural Resources Wales, the Scottish Environment Protection Agency (SEPA) and the Department for Infrastructure in Northern Ireland.

From the Environment Agency’s Flood Map for Planning, as republished in the flood-risk-zone dataset on planning.data.gov.uk under the Open Government Licence. The Environment Agency updates the map periodically and the national dataset follows, so there can be a short lag. The official Flood Map for Planning is always the final word.

No. It’s an independent check built from official open data. For a planning application, a mortgage or a purchase you may need a site-specific flood risk assessment or an environmental search, and you should confirm the zone on the Environment Agency’s own map.