Flood Risk: Buying a Property at Risk of Flooding

flood risk

Buying a house is stressful and often long and costly process. There are a huge number of variables to consider which should include flood risk. Once your heart is set on somewhere it is easy for the focus to shift solely to securing an exchange date and collecting the keys. Potential issues raised through the surveying and conveyancing process may be dismissed. Issues maybe thought of as only a minor inconvenience or considered part and parcel of any property purchase. The fear of missing out, especially within a competitive housing market, means buyers may take risks on properties.

When it comes to flooding it is important that the risks are fully understood. The financial and emotional costs may not be a risk worth taking.

Understanding Flood Risk

It is easy to understand why possible flooding may be dismissed or downplayed; during a property viewing the current owner might state “we’ve never flooded in 20 years”, an internet search does not find any historic news reports relating to flooding, and all the flood map searches show that there is only a “Low Risk”. Surely that means there is nothing to worry about, right? Possibly, but surely you want the peace of mind when making such a big investment decision.

Currently around 5.2 million homes in England, or one in six properties, are at risk from flooding.

It is important to understand that the limitations of the flood risk information provided within the standard set of property searches. The classification of flood risk to a property is typically based on national scale flood mapping produced by the Environment Agency in England, Natural Resources Wales in Wales and the Scottish Environment Protection Agency in Scotland. These flood maps are typically poor at assessing and determining flood risk at the site scale. They often do not account for local characteristics such as small variations in ground levels, informal flood defences, or existing drainage arrangements so only offer a more general overview of risk.

Flooding Reports

A recent article published by insurance firm Zurich explains how and why flood risk is so poorly understood.

The Environment Agency currently reports flooding risks based on the chances of an area flooding in any one year. It rates homes with a so-called 1 in 100-year to a 1 in 30-year chance of flooding as being at “medium” risk. This means there is a 1% to 3.3% chance of a flood occurring in any single year.

But Zurich has warned that when viewed over a typical 30-year mortgage, this equates to a 26% and a 63% likelihood of being flooded once in that period. This is actually a far greater risk than the current terminology suggests. Zurich said this could leave homebuyers with a misleading impression of their flood risk and lull them into a false sense of security. 

Flood modelling, mapping and forecasting is not an exact science. The risks can be both understated and exaggerated depending on numerous factors.

Flood maps are also unable to provide an indication of what the impacts of a flood might be. For example, would flood water stay out of the property when the garden becomes inundated? What could the potential flood depths be?

Understanding the potential impacts is particularly important. If the potential impacts are low, the risk could be considered less of a problem, and more manageable. However, if the potential impacts are high, the disruption and costs could become significant.

Flood Damage

Flooding may not be a regular occurrence, but when it happens it can be devastating. When flood water enters the home it devastates the whole ground floor, damaging and destroying fixtures, fittings, furniture and electricals. Dirty contaminated water can leave a thick sludge and a horrendous stench.

The subsequent clean-up costs can grow exponentially. The damage may be such that floors, kitchen units and plasterboard need to be removed. Furniture, belongings, and white goods may be damaged beyond recovery or repair. To allow a property to dry out following a flood, the occupants may need to move out, causing huge disruption which can extend to months and even years.

The cost is not just financial; the upheaval and effort to recover following a flood can be hugely stressful and emotional. If not prepared the looses can also include items that are irreplaceable like family photos, gifts from loved ones and other items!

It is for these reasons it is always recommended to get a detailed understanding of the flood risk to a property before you buy.

The Next Steps: Flood Risk Management

A RICS property survey or a study undertaken by a qualified flood risk consultant can help assess the potential impacts of flooding and provide recommendations to help minimise these should a buyer chooses to proceed.

A Property Flood Resilience Survey can also be completed to determine how resistant or resilient the property may be to flooding. It will also cover what additional measures could be implemented to minimise the risk.

Flood risk can be managed in numerous ways. Resistance measures such as flood walls, flood barriers and flood doors aim to prevent water entering the home. Resilience measures may include specifying water resistant fixtures and fittings which ensure that the impacts are minimised when water ingress does occur.

The Royal Institution of Chartered Surveyors advise that flood risk could seriously impact the value of a property, should you compare it with a similar property of a lower risk. A suitable risk study and survey may even provide an angle for negotiation if the risk can be managed.


The flood modelling and mapping used within standard property searches is often not reliable. If you are thinking of buying a new home and have even the slightest of concerns regarding the potential flood risk, it is typically always worth seeking the advice of a professional flood risk consultant to ensure your dream move does not become a nightmare.

Article by Simon Crowther BEng (Hons) MCIWEM C.WEM. Simon is a Flood Risk Consultant, Civil Engineer and Chartered Water & Environmental Manager. His team work both Nationally and Internationally to help clients better understand flood risk before looking into flood mitigation options.

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