Flood risk: what to check before you buy

Before you buy, check the property's flood risk using official flood maps, your conveyancer's environmental search and the seller's answers about past flooding, then get buildings insurance quotes before you exchange. Your surveyor will flag obvious signs and risks, but a house survey is not a flood risk assessment. Flood risk affects insurance, mortgages and resale, so it is worth checking early.

Key points

• Check river, sea, surface water and groundwater flood risk separately.
• In England use GOV.UK flood maps, and in Wales use Natural Resources Wales maps.
• Ask the seller about past flooding and any insurance claims.
• Get insurance quotes before exchange. Flood Re helps many homes built before 2009.
• Surveyors flag visible signs of flooding, but cannot assess the full risk.

What types of flooding should you check?

Flood risk is not just about living next to a river. The main types are:

• Rivers - flooding when rivers overflow their banks.
• Sea - coastal and tidal flooding, often during storms.
• Surface water - heavy rain overwhelming drains and collecting in low spots, which can affect properties far from any watercourse.
• Groundwater - rising water tables, particularly in chalk areas, which can flood basements and ground floors.
• Reservoirs - an unlikely but possible risk if a dam failed.
• Sewer flooding - drains backing up during heavy rain.

How do you check flood risk?

Official flood maps

In England, the GOV.UK "check long term flood risk" service shows the risk from rivers, the sea, surface water, reservoirs and groundwater for a specific address or postcode. In Wales, Natural Resources Wales provides equivalent flood risk maps. These give risk bands such as high, medium, low and very low.

Your conveyancer's searches

Ask your conveyancer for an environmental search that includes flood risk. Many search providers combine Environment Agency data with other data sets and give an overall risk score, sometimes with insurance guidance.

The seller's property information form

The TA6 form asks whether the property has flooded, what type of flooding it was, and whether a flood risk report has been prepared. Ask for details of any claims and repairs.

Local knowledge

Talk to neighbours, look at local news and check whether the property has flood defences such as flood doors or non-return valves on drains. These can be clues to past problems.

What can a surveyor tell you about flooding?

During a Level 2 Home Survey or Level 3 Building Survey, the surveyor will look at the property's setting and the building itself. They may note:

• Proximity to rivers, streams, the coast or low-lying land.
• Signs of past flooding, such as tide marks, replaced plaster at low level, new floors or recently renovated ground floors.
• Flood resilience measures, such as raised electrics, flood doors and air brick covers.
• Poor drainage around the house, blocked gullies or ground sloping towards the walls.
• Damp affecting ground floors and basements.

Surveyors often refer to flood risk information in their report and may recommend that your conveyancer checks it. But they do not carry out a detailed flood risk assessment. If the risk looks significant, you may want a specialist flood risk report.

How does flood risk affect insurance?

Flood risk can make buildings and contents insurance more expensive or harder to find. Flood Re is a joint scheme between the government and insurers that helps make flood cover more affordable for many households at high risk. Key points:

• It generally applies to residential properties built before 1 January 2009.
• Homes built after that date are not covered by Flood Re, on the basis that they should have been built with flood risk in mind.
• Flood Re is designed as a transitional scheme and is due to run until 2039.

Always get insurance quotes before you exchange contracts, because you will normally be responsible for insuring the property from exchange.

How does flood risk affect your mortgage?

Lenders want to know the property is insurable. If you cannot get reasonable buildings insurance, you may struggle to get a mortgage. Some lenders also take flood risk into account in their valuation. Speak to your broker if a property is in a high risk area.

What about future flood risk?

Climate change is expected to increase the frequency and severity of some types of flooding, particularly surface water and coastal flooding. Some environmental searches include future climate risk projections. If you are planning to stay long term, it is worth considering.

What if a property has flooded before?

A past flood does not automatically rule out a purchase. Ask:

• When did it flood, how badly, and from what source?
• What repairs were done, and by whom?
• Were flood resilience measures installed?
• Is there insurance in place, and will the insurer offer cover to you?
• Have flood defences been improved since?

Use what you find in any renegotiation, and see our guide on whether to pull out after a survey if the risk feels too great.

What flood resilience measures should you look for?

If a property is in a higher risk area, measures that reduce damage and recovery time can make a real difference, and some insurers take them into account. Look for:

• Flood doors or removable flood barriers for doorways.
• Self-closing or covered air bricks that stop water entering through ventilation.
• Non-return valves on drains and toilets to prevent sewage backing up.
• Raised electrical sockets and a consumer unit positioned above likely flood levels.
• Solid floors and water-resistant finishes on the ground floor, such as tiles rather than carpet, and lime or cement-based plaster.
• A sump and pump in basements.

Ask the seller whether any of these were installed after a flood survey, and whether they were part of a grant-funded scheme. Your surveyor can comment on what they see.

Flooding and damp

Flood water can leave walls damp for months and may cause hidden damage to floors and timbers. If the property has flooded, your surveyor's comments on damp are particularly important.

If you want a local surveyor to look at a property before you commit, get a fixed-price survey booked and we will arrange access with the estate agent.

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