Exception Test evidence and site-specific Flood Risk Assessments for development that cannot be located in lower flood risk areas.
The Exception Test is the second stage of the planning system’s flood risk hierarchy, applied after the Sequential Test has been satisfied. Where the Sequential Test asks whether development can be steered to a lower risk site, the Exception Test asks whether, given that it cannot, the proposed development should still be permitted on flood risk grounds.
The test was deliberately designed to allow only those developments that bring wider benefits and can be made demonstrably safe for the lifetime of the proposal. Where it applies, the evidence base needs to be technically robust, proportionate, and clearly aligned with the NPPF. We prepare that evidence for clients across the UK, working alongside planning consultants, architects and developers to produce Exception Test submissions that hold up to scrutiny.
For broader scoping advice or applications that fall outside the Exception Test, our Flood Risk Assessment service page sets out the full range of FRA work we deliver and is the appropriate starting point for most enquiries.
The Exception Test is set out in paragraphs 177 to 179 of the NPPF[SC1.1]. To pass, two elements must both be demonstrated:
• the development would provide wider sustainability benefits to the community that outweigh the flood risk; and
• the development will be safe for its lifetime, taking account of the vulnerability of its users, without increasing flood risk elsewhere, and where possible will reduce flood risk overall.
Both elements must be satisfied. Failing either means the test is not passed.
The first element is largely a planning matter. Wider sustainability benefits can include the re-use of brownfield land as part of a regeneration scheme, contributions to flood risk management infrastructure, or the provision of multifunctional sustainable drainage that significantly exceeds policy requirements. The planning consultant typically leads on this argument, drawing on the local plan and sustainability appraisal framework.
The second element is where our work sits. Demonstrating lifetime safety requires a site-specific Flood Risk Assessment that addresses flood depth, velocity, risk, speed of onset, safe access and egress (with a Flood Warning & Evacuation Plan), residual risk, and the management of risk over the design life of the development, including climate change allowances. Where the development will reduce flood risk overall, that needs to be evidenced and quantified.
The Exception Test is not a route to justify development that has already failed the Sequential Test on its merits. It is only appropriate where the Sequential Test has been satisfied, the development must be located in a flood risk area, and the wider sustainability case is genuine.
Whether the Exception Test is needed depends on the flood zone and the vulnerability classification of the development, as set out in Annex 3 of the NPPF and Table 2 of the PPG (Planning Practice Guidance).
The test is required for:
• More Vulnerable development in Flood Zone 3a, including most residential development and residential institutions
• Highly Vulnerable development in Flood Zone 2, including basement dwellings and certain forms of essential infrastructure
• Essential Infrastructure in Flood Zones 3a and 3b
It is not required in Flood Zone 1, and is not triggered for changes of use under the NPPF. Highly Vulnerable development is not permitted at all in Flood Zone 3a or 3b, and More Vulnerable development is not permitted in Flood Zone 3b.
In practice, the Exception Test is most often encountered on residential schemes in Flood Zone 3a, and on conversions where the proposed use is more vulnerable than the existing use. We see it regularly on barn conversions and on change of use applications where the building sits in a higher risk zone.
It also applies to new build residential development in Flood Zone 3a, where we work directly with architects and developers to integrate the flood risk evidence into the design from the outset rather than retrofit it at submission.
The Exception Test should also be read alongside the Sequential Test, including the September 2025 update set out in our Sequential Test 2025 article. Where the Sequential Test is not required following that update, the Exception Test is generally not required either, but the underlying lifetime-safety demonstration remains the same technical exercise.
We investigate how sites behave. Flooding, drainage performance, levels and constraints. That insight feeds directly into our work, whether for planning, design or resolving existing issues.
For existing sites, our investigative work typically takes the form of a flood survey or a flood investigation and management strategy. These services are for sites that have flooded, are flooding, or where an owner needs to understand what is happening in order to manage it.
For development sites, the equivalent work is a Flood Risk Assessment, prepared to support a planning application. That is where the Exception Test sits, and where we work most regularly with architects and developers to embed flood risk evidence into the design.
We deliver this work across the UK, with project locations ranging from Cumbria to Cornwall. The technical approach is consistent.
The local regulatory landscape varies, and we adjust pre-application engagement accordingly.
Years combined civil & environmental engineering experience
Years delivering drainage, design and risk advisory
Projects including individual assets valued at £1 billion+
Drainage design and flood risk commissions delivered
Here are some of our latest testimonials from satisfied clients. If you’d like to discuss your requirements further, please don’t hesitate to get in touch.
We are a charity owning a large parcel of land where gathering water is then affecting neighbouring properties. Received expert flood risk and drainage advice from FPS Environmental Ltd. All dealings with them were timely and professional. Site visit arranged where we were able to fully discuss causes and solutions. Great peace of mind obtained from engaging their expertise.
Michael Rowell
Landowner
The report I received was for a Flood Survey which was very thorough and clearly a lot of work had gone into it. The team were always available and conscious of deadlines. I would definitely recommend them if you are looking to get a flood survey completed.
Mike Gray
We spent thousands of pounds on poor quality investigations before reaching out to FPS Environmental. Most surveyors over promised and underdelivered creating tremendous stress for me and my family. FPSE has been absolutely amazing from the very beginning. They treated us with respect and restored our faith in this industry. We are incredibly grateful to them and highly recommend the company to anybody who wants to get a top product and piece of mind.
George Albota
I have used FPS, Simon and his team on several occasions over the last few years to advise on the flood risk and mitigating factors on both houses and prospective businesses. They have deep expertise and contacts across the spectrum of flood management. In particular, I have found their assessment reports invaluable. Whilst they are understandably busy, they are good to deal with and I would have no hesitation recommending them to anyone who is looking for advice in the sector.
Richard Warburton
Business Owner
FPS was really helpful in providing consulting advice in connection with a residential property acquisition. Sebastian from FPS undertook the survey and followed up with a full report and a consultation call to run through everything. The basic desktop data suggested a high flood risk, but this property-specific survey allowed us to take a well-informed position following Sebastian’s advice. Great work – and he and the FPS team were really helpful throughout the process. I’d certainly recommend them.
Richard Brandon
Very impressed with FPS Environmental Ltd and the guidance we have received to date. We had an hour long online consultation with the principal surveyor, and it was extremely helpful and productive. Thank you FPS. Will use the company again and highly recommend.
Helen Sutherland
FPS were able to work to our schedule and fit in an appointment at short notice. There was great communication from the office staff keeping us informed of any changes or requirements before the site visit.
The site survey was very thorough and Simon very knowledgeable, and quite happy to answer all questions. The provided report was extensive with usable information and recommendations. I will use FPS in the future and happily recommend them to all of my clients.
Drew Kirkland-Crawford
Deadwood Services Ltd
Send us your project brief and we will come back with a scope and indicative fee. Where additional input is required, this is provided on a formal instruction basis.
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