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- The NPPF's New Flood Risk Rules: What Every Developer Needs to Know
The Government's August 2026 update to the National Planning Policy Framework (NPPF) introduces the most significant changes to flood risk policy in years.
While planning reform and housing targets have dominated headlines, developers should pay close attention to the new flood and drainage requirements, which place greater emphasis on early risk assessment, site design and long-term resilience.
What has changed?
Flood risk and coastal change policies are no longer grouped within broader climate change guidance. Instead, the revised NPPF introduces a dedicated flood risk chapter (Chapter 18), giving the subject greater prominence and ensuring flood considerations play a more central role in planning decisions.
Flood risk is now covered under a series of dedicated policies, F1 through F9, which address:
Flood Risk Assessments (FRAs)
The Sequential and Exception Tests
Development safety requirements for its lifetime
Sustainable Drainage Systems (SuDS)
Coastal change considerations
The biggest change is that flood risk and drainage is now expected to influence site design rather than be seen as a technical challenge to overcome. This new structure provides greater clarity for applicants and planning authorities alike.
Why Flood Zone 1 Doesn't Always Mean Low Risk
Many developers assume that if a site sits within Flood Zone 1, flood risk won't be a planning concern, which can lead to applications progressing without a full understanding of the risk.
The revised framework gives greater recognition to other sources of flooding, particularly surface water flooding, which affects many urban development sites, removing the age-old rule of Flood Zone 1 or under 1.0ha.
As a result, some sites may still require a Flood Risk Assessment despite being outside river flood zones or nowhere near water.
Drainage Takes the Lead
Sustainable drainage is no longer simply a box-ticking exercise.
The updated NPPF strengthens requirements around SuDS design, performance and long-term maintenance. Under Policy F8, drainage strategies are expected to demonstrate compliance with the National Standards for Sustainable Drainage Systems and show how surface water will be managed throughout the lifetime of the development.
At the same time, the industry is preparing for the implementation of Schedule 3 of the Flood and Water Management Act, which will introduce a dedicated approval process for drainage systems and place even greater emphasis on the design, adoption and maintenance of SuDS.
Both of these put greater emphasis on early-stage drainage design and coordinated engineering input. The days of simply demonstrating a discharge rate and adding an attenuation tank are rapidly disappearing. Planning authorities and regulators increasingly want to understand how a development manages water across the entire site and how that solution will continue to function decades into the future.
Development Safety
The updated NPPF puts much greater emphasis on the actual safety of the development throughout its lifetime, including future climate change impacts. Policy F7 requires developments to be safe without increasing flood risk elsewhere. In practical terms, planners, the EA and LLFAs are increasingly asking:
Can residents escape safely?
Can emergency services access the site?
What happens if drainage exceeds design capacity?
What happens during a 1-in-100 plus climate change event?
Will flood water be routed away from buildings?
Are vulnerable users protected?
The industry conversation is often centred on where flood water goes. Our focus is on what happens when it gets there.
For years, our specialists have assessed flood depths, velocities and hazard ratings to understand how people, vehicles and emergency services can safely access and use a development during severe weather events. The increased emphasis on development safety within the NPPF simply reinforces an approach we have already been delivering for our clients across a wide range of residential, commercial and infrastructure projects.
Our Advice?
The result of all this is that flood risk assessments are increasingly becoming a site design tool, rather than simply a planning requirement.
Whether you're promoting a strategic site, preparing a planning application or assessing development potential, our flood risk and drainage specialists can identify risks early and develop practical solutions that support successful planning outcomes.
The most successful planning applications under the new NPPF are likely to be those that:
Screen flood risk early through Curtins Foursite offering
Assess all flood sources, not just rivers, including detailed GIS overlays
Develop drainage strategies alongside site layouts
Resolve planning risks before submission
Whether you're assessing development potential, preparing a planning application, or responding to local authority requirements, our team can help.
Our Foursite service is Curtins' innovative approach to due diligence, pre-planning, site feasibility studies and other pre-acquisition and development services.
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