What does flood risk mean when you are buying a house?
A high flood risk means the area around the home has more than a 3.3% chance of flooding in any year. Flood zone 3 is a planning term: at least a 1% yearly chance of flooding from rivers, or 0.5% from the sea.
Flood zones ignore flood defences, while the risk levels allow for them. Before you offer, check the surface water risk too, and ask whether the home has ever flooded.
What the flood risk levels mean
In England, the Environment Agency gives each area a risk level for rivers and the sea, and a separate one for surface water. The levels are based on the chance of flooding in any one year.
| Risk level | Chance of flooding each year | Chance over 25 years |
|---|---|---|
| High | More than 3.3% | More than 57% |
| Medium | 1% to 3.3% | 22% to 57% |
| Low | 0.1% to 1% | 2.5% to 22% |
| Very low | Less than 0.1% | Less than 2.5% |
Yearly chances from the Environment Agency. The 25-year column is our arithmetic, assuming the yearly chance stays the same, so treat it as an illustration.
Over 25 years, an area at medium risk has between a 22% and 57% chance of at least one flood.
The Environment Agency and Natural Resources Wales both say their maps show the risk for an area, not for an individual property. The building itself may sit higher or lower than the land around it.
Our free check shows both risk levels for the area around a home in England or Wales, from the Environment Agency or Natural Resources Wales.
It also shows any flooding they have recorded at the home's position. In England you can ask the Environment Agency for a flood history report for the area around an address, which takes up to 20 working days and may carry a fee.
Our guide to finding out if a house has flooded before explains what these records show and what they miss.
Flood zones are a different measure
Flood zones come from the Flood Map for Planning. Councils use them when deciding planning applications, and you may see them in a search or a listing.
| Zone | What it means |
|---|---|
| Zone 1 | Less than a 0.1% yearly chance of flooding from rivers or the sea |
| Zone 2 | Between 0.1% and 1% from rivers, or between 0.1% and 0.5% from the sea |
| Zone 3a | 1% or more from rivers, or 0.5% or more from the sea |
| Zone 3b | Functional floodplain: land where water has to flow or be stored in a flood |
Sources: Planning Practice Guidance, Table 1, National Planning Policy Framework, Annex F.
They only cover rivers and the sea, and they ignore flood defences. The risk levels allow for defences, so a home in flood zone 3 can still show a low risk.
Nor do flood zones allow for climate change. Since August 2025 the Flood Map for Planning has also shown how zones 2 and 3 could grow with climate change, so check both layers.
A home can also be in flood zone 1 and still be at high risk from surface water.
Surface water: risk away from rivers
Surface water flooding happens when heavy rain falls faster than the ground and drains can take it. It can affect streets far from any river.
The Environment Agency's December 2024 assessment found about 4.6 million properties in England in areas at risk of surface water flooding. That is more than the 2.4 million it found at risk from rivers and the sea.
In total, it found 6.3 million properties in areas at risk from one or more sources, and said this could rise to about 8 million by the middle of the century.
If the home is in Wales
Natural Resources Wales publishes its own flood map. It gives risk levels for rivers, the sea, and surface water and small watercourses. For reservoirs it shows only the area that would flood if a large reservoir failed.
Its bands are similar to the Environment Agency's.
Insurance and Flood Re
If you are buying a house, you need buildings insurance from the day you exchange contracts. In a medium or high risk area, get a quote for the exact address before you commit.
For a leasehold flat, GOV.UK says the landlord usually insures the building, paid for through the service charge. Ask for that policy and its flood excess instead.
Flood Re is a scheme that helps insurers offer cover to homes at flood risk. To qualify, a home must have been built before 1 January 2009, and be a single home or a building of two or three homes.
So a newer home near water cannot benefit, and Flood Re says it would not expect blocks of more than three flats to qualify for buildings cover. It plans to run until 2039.
Add the insurance quote to your budget, with the other costs in our guide to the total cost of buying a house.
What to do if the risk is medium or high
A medium or high level is not, on its own, a reason to walk away. It means you need answers before you offer.
| Check | Who to ask |
|---|---|
| Has the home ever flooded, inside or in the garden? | The agent, then the seller in writing |
| Have there been any insurance claims for flooding? | The seller |
| What does buildings insurance cost, and what is the flood excess? | An insurer or broker, for the exact address |
| Was the home built before 2009, so Flood Re can apply? | The agent. The energy certificate gives an age band, which our free check shows |
| Are there flood doors, air brick covers or non-return valves? | The seller, and your surveyor |
| What did the seller say about flooding on the property information form? | Your conveyancer |
At the viewing, look for tide marks and new skirting boards low on the walls. Our viewing checklist adds these checks for homes in flood risk areas, and our questions for the agent cover past floods and claims.
Mention the flood risk to your surveyor before the visit, as RICS's standard terms ask you to share particular concerns. See which survey you need.
Your conveyancer can also order a flood search with the other searches.
If an answer arrives after your offer is accepted, you can still renegotiate, because nothing is binding until exchange. See how offers work and the other checks to do before you offer.
Ask the agent
- Has the property, the garden or the road outside ever flooded?
- Has the seller made any insurance claims for flooding?
- What does the seller pay for buildings insurance, and what is the excess?
- Has any flood protection been fitted, and is there paperwork for it?
Related questions
Does a low flood risk mean the home will not flood?
No. Low still means a 0.1% to 1% chance each year for the area. The national maps also do not cover flooding from blocked drains or burst pipes, so ask about the home's own history.
Can I get a mortgage on a home in a high flood risk area?
It depends on the lender. For a house, you will usually need buildings insurance from exchange of contracts, so get a quote for the address first. For a leasehold flat, the landlord usually insures the building.
Does Flood Re cover every home?
No. Only homes built before 1 January 2009 can qualify, and there are other rules, so check its criteria before you rely on it.
Sources
- GOV.UK, Check your long term flood risk
- Environment Agency, What the flood risk levels mean
- GOV.UK, Flood risk and coastal change (planning guidance)
- GOV.UK, National Planning Policy Framework, Annex F: managing flood risk and coastal change
- Environment Agency, National flood risk assessment update, December 2024
- Natural Resources Wales, Understanding your flood risk results
- Natural Resources Wales, Flood Risk Assessment Wales map
- Flood Re, Eligibility criteria
- Flood Re, About us
- data.gov.uk, Flood Map for Planning: flood zones plus climate change
- Environment Agency, Risk of flooding from rivers and sea (dataset)
- GOV.UK, Find out if your property is in an area that has flooded
- Environment Agency, Recorded Flood Outlines (data.gov.uk)
- GOV.UK, How to buy a home
- GOV.UK, Leasehold property: service charges and other expenses
- Environment Agency, Flood Map for Planning: flood zones (data.gov.uk)
- RICS, Description of the RICS Home Survey Level 2 (survey only)