Navigating the Future of Housing: Why Better Data Means Safer New Builds
Following Aegaea’s Director, Daniel Cook, on ITV’s Tonight, we explore how improved flood data is reshaping risk and supporting safer development.
Following Daniel Cook’s recent appearance on ITV’s Tonight programme, where he discussed the challenges surrounding new build flood risk, this article explores the wider context behind some of the headline statistics and how improved flood data is shaping safer development decisions.
Flood risk is understandably a sensitive topic for homeowners, planners and developers alike. However, as flood modelling and national datasets continue to evolve, it is important to recognise that many of the changes being reported are the result of better data and improved understanding, rather than a sudden increase in flooding itself.
Why Improvements in Flood Data Matter
Recent updates to national flood risk datasets show that more properties are now identified as being at risk of flooding across the UK.
Much of this change is linked to improvements in flood modelling techniques and higher-resolution mapping.
One key improvement has been the removal of a modelling limitation known as “deflection”, where earlier surface water models diverted floodwater around buildings instead of showing how water could interact with them.
As the Environment Agency explains:
“Our previous surface water flood risk maps were limited in the way they deflected water around the walls of buildings. This meant that the properties themselves did not appear to be at risk of flooding on the maps. The new mapping removes this limitation, making it a more realistic local assessment of surface water flood risk.”
Alongside this change, improvements in rainfall modelling, climate projections and high-resolution terrain data have also influenced the number of properties identified as potentially being at risk – particularly from surface water flooding, which is one of the most complex forms of flooding to predict.
Current national assessments suggest:
- 4.6 million properties are now identified as being at risk of surface water flooding – a 43% increase from previous modelling
- 1.1 million properties are classified as being at high risk of surface water flooding
At first glance, these figures may appear concerning. However, they largely reflect better visibility of risk rather than a sudden increase in real-world flood events.
In simple terms, the data has improved – and we are now able to see the risk more clearly.
For planners, engineers and flood consultants, this improved clarity is extremely valuable. Better data allows developments to be designed with more accurate drainage strategies, stronger mitigation measures and greater long-term resilience.
This is also why national studies such as the National Flood Risk Assessment (NaFRA) are so important. They provide a national framework that helps inform planning policy, risk management strategies and future development planning.
The Planning System Is Robust, Not Relaxed
There is sometimes a perception that the UK planning system is becoming more permissive when it comes to building in flood-prone areas. In practice, the planning framework continues to apply multiple layers of policy and technical scrutiny.
Flood risk planning decisions are shaped by several key policy frameworks, including:
- The National Planning Policy Framework (NPPF)
- Planning Practice Guidance (PPG)
- Local Plans and Supplementary Planning Documents
At the centre of the system is the Sequential Test, which aims to steer development towards areas with the lowest probability of flooding wherever possible.
Where development in higher-risk areas cannot be avoided, developers must demonstrate through a Flood Risk Assessment (FRA) that:
- the development will remain safe for its lifetime
- flood risk will not increase elsewhere
- appropriate mitigation measures are in place
It is important to understand that an FRA is not simply a document submitted to support a planning application. It is a technical risk assessment, and its conclusions are carefully reviewed by planning officers, regulators and, where appropriate, the Environment Agency.
In some cases, flood risk can be mitigated through engineering design, drainage infrastructure or site layout adjustments. However, planning consent should only be granted where policy requirements are clearly satisfied.
Geographical constraints also play an important role in development decisions. Certain coastal or low-lying towns, such as Eastbourne or Boston, have limited development land due to surrounding watercourses, tidal influence or local topography.
In these situations, development proposals must demonstrate particularly robust mitigation measures before approval is considered.
Putting the “One in Nine Homes” Headline Into Context
A recent analysis by Aviva suggested that one in nine homes built between 2022 and 2024 are located in areas classified as medium or high flood risk.
Statistics like this understandably attract attention, but they can oversimplify a complex issue.
Flood risk classification does not automatically mean unsafe development. Modern planning policy, engineering design and flood modelling are specifically intended to identify, manage and mitigate risk through measures such as drainage strategies, finished floor levels and site design.
It is also worth noting that datasets used in this type of analysis typically rely on completed homes recorded in Ordnance Survey AddressBase. These properties may have been granted planning permission several years earlier, during which time flood modelling, national datasets and planning guidance may have evolved significantly.
A good example of this is the recent updates to the National Flood Risk Assessment (NaFRA2), which have refined flood modelling across England and resulted in larger areas being identified as at risk of flooding. As a result, some properties now shown within flood risk areas may not have been identified as being at risk when planning permission was originally granted several years ago.
This highlights an important point: flood risk is not static. Improvements in data, modelling techniques and national guidance can change how risk is understood over time, which is why site-specific assessment remains critical when considering both existing and future development.
In addition, broad classifications do not always reflect the depth or probability of flooding. In some cases, sites may only intersect with very low-probability events – for example a 1 in 1000 year surface water scenario with shallow depths. Some may be in medium and high risk areas, it doesn’t stop development, mitigation techniques could exist as the whole site is not affected or the depths are able to be mitigated within the wider site.
This of course does not diminish the importance of managing flood risk. Rather, it highlights why planning decisions rely on detailed Flood Risk Assessments and site-specific modelling, rather than headline statistics alone.
Surface Water Management in New Developments
Surface water drainage is one of the most important aspects of flood risk management for modern housing developments.
When drainage systems fail, the consequences can be significant. As a result, the industry has been steadily strengthening oversight and accountability.
One example is the increasing use of Verification Reports, which confirm that Sustainable Drainage Systems (SuDS) approved during the planning process are installed correctly during construction.
Looking ahead, the proposed implementation of Schedule 3 of the Flood and Water Management Act is expected to introduce SuDS Approving Bodies (SABs). These bodies will review and approve drainage proposals before construction begins.
These changes reinforce an important principle: drainage infrastructure must not only be designed correctly, but also delivered correctly on site.
Planning for Housing and Climate Resilience
The UK government has set a target of delivering 1.5 million new homes.
At the same time, national flood modelling suggests that the number of properties identified as being at risk of flooding will continue to increase as datasets improve and climate projections evolve.
These two realities are not necessarily in conflict.
Planning decisions themselves often take months (and sometimes years) to progress, and the data used to inform those decisions continues to evolve during that time.
Flood maps are updated, modelling techniques improve and datasets such as NaFRA are refined.
This evolving understanding allows developments to be designed with greater resilience and more informed risk management.
Flood risk therefore needs to be understood, planned for and designed around, rather than treated as an automatic barrier to housing delivery.
Interpreting Flood Risk Data in Practice
At Aegaea, much of our work involves helping developers, planners and landowners interpret complex flood datasets and planning requirements so that development can move forward safely and responsibly.
This includes translating evolving national data, including updates to NaFRA and surface water flood modelling, into site-specific Flood Risk Assessments, drainage strategies and resilient design solutions.
With development pressures particularly strong in London and the South East, understanding how flood modelling, planning policy and drainage design interact is becoming increasingly important.
Flood risk conversations are rarely simple, and the data will continue to evolve. But better data ultimately supports better decisions, better design and safer places to live.
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