Flood Risk Assessment for BREEAM

A BREEAM flood risk assessment is a site-specific study prepared to support the Pol 03 (Flood and surface water management) credit under BREEAM, and it is not the same document as the flood risk assessment you submit for planning. Both look at the same site and use much of the same flood data, but they are scored by different people against different tests, which is exactly where credits get lost when the work is treated as one job. Unda prepares BREEAM FRAs that are built for how an assessor reads them, so the evidence lines up with the credit criteria rather than the planning case.

We have completed more than 5,000 flood risk assessments since 2014, working across England and Wales for developers, architects and sustainability consultants. Our reports are written by CIWEM-qualified flood risk consultants and, where a scheme needs it, paired with a drainage strategy from the same team so the flood risk and surface water evidence tells one consistent story.

The credits a scheme can earn are largely decided before you design anything: by the site's pre-development flood risk, not by how good the mitigation is.

What is a Flood Risk Assessment for BREEAM?

A BREEAM flood risk assessment is a site-specific technical study that establishes the flood risk to a development from every relevant source and shows how the design responds, prepared and presented so it supports the Pol 03 credit. It sits inside BREEAM's pollution category and is assessed by your BREEAM assessor against the Pol 03 criteria, not by a local planning authority or the Environment Agency.

That distinction matters more than it first appears. A planning FRA is written to satisfy the National Planning Policy Framework and its "safe for its lifetime" test; a BREEAM FRA is written to earn credits, and the number of credits available turns on how the site is classified before development. A strong planning flood risk assessment usually supplies most of the evidence an assessor needs, but only if it was set up to answer BREEAM's questions as well as the planner's. Get that wrong and you can hold a perfectly good planning consent and still lose points on the certificate.

BREEAM Pol 03 explained

Pol 03 is titled Flood and surface water management, and it rewards designing a building that manages flooding and surface water well. It has three connected parts, and a BREEAM FRA feeds the first two directly:

• Flood risk. The scheme is judged against the site's flood risk, established from its flood zone and the sources of flooding present. Where a site spans more than one flood zone, the highest-risk zone applies unless there is justification to treat it otherwise.
• Surface water run-off. The design has to show that post-development run-off rates and volumes are held at or below the pre-development position, benchmarked against The SuDS Manual (CIRIA C753) and delivered through sustainable drainage.
• Minimising watercourse pollution. The scheme demonstrates that surface water leaving the site will not pollute receiving watercourses, through source control and an appropriate treatment train.

The exact credit references, thresholds and the number of points on offer depend on the BREEAM version and scheme you are certifying under, so we confirm those against the live BREEAM Pol 03 criteria for your project rather than assume them. Flood-resilient design — safe finished floor levels, resilient construction — can also feed BREEAM's climate-change adaptation credit, so the same assessment often earns its keep in more than one place.

How pre-development flood risk sets the credit ceiling

This is the single most important thing to understand about Pol 03, and the reason we push clients to commission early. The flood-risk credits are pegged to the site's pre-development flood risk classification — the risk before you build. A site that classifies as low risk keeps the full set of flood-risk credits in play; a medium or high classification restricts them, and no amount of clever mitigation lifts that ceiling back up. Mitigation keeps the building safe; it does not re-open credits the baseline has already closed.

Because the classification is fixed so early, the best time to have it pinned down is at concept design, while the layout is still flexible. If a site is low risk, you want that recorded and defended before anyone assumes otherwise; if it is not, you want to know while there is still room to respond in the masterplan.

BREEAM FRA or planning FRA: which do you need?

Most schemes that need a BREEAM FRA also need, or already have, a planning FRA, so the practical question is rarely one or the other, but whether a single assessment can serve both. It usually can, if it is scoped that way from the start. The table sets out where the two differ.

For a fuller walk-through of the differences, our guide on BREEAM flood risk assessments explained covers the credit mechanics in more depth. If your development is in Wales, the planning equivalent is a Flood Consequence Assessment rather than an FRA, and the BREEAM assessment sits alongside it in the same way.

Is a BREEAM FRA the right assessment for you?

"Flood risk assessment" covers several different reports that answer different questions. If you have landed here but your need is not really about BREEAM credits, one of these is the report you are after:

• You need permission for a scheme in Flood Zone 2 or 3. That is a flood risk assessment for planning, written to the NPPF — and often the foundation a BREEAM FRA builds on.
• Your site is in Wales. You need a Flood Consequence Assessment under TAN15 and Planning Policy Wales.
• The planning FRA has flagged a need to test alternatives. That is a Sequential and Exception Test.
• You are buying a property flagged for flood risk. A flood risk survey for property purchase answers the buyer's question, not the planner's.
• An insurer or lender has raised flood risk. An independent flood risk assessment for insurance gives them property-level evidence.
• The national maps do not reflect your site. Bespoke flood modelling can quantify levels, extents and depths where standard data falls short.
• The issue is really surface water and drainage. A sustainable drainage strategy is what proves run-off control — and it is the natural partner to the surface water half of Pol 03.

Not sure which of these fits? Contact us with a sentence about your project and we will point you to the right report before you spend anything.

When do you need a Flood Risk Assessment for BREEAM?

You need a BREEAM FRA when a project is pursuing BREEAM certification and Pol 03 is in play — which, for most new-build schemes, it is. The common triggers are straightforward:

• New-build development targeting a BREEAM rating. Wherever Pol 03 credits are being pursued, a compliant site-specific FRA is the evidence behind them.
• Flood risk is affecting the credits you can reach. If the target rating depends on Pol 03 points, the flood risk classification needs to be established and defended, not assumed.
• You have a planning FRA that does not meet BREEAM's requirements. An assessment that is silent on a flood source, or built only on published maps, may satisfy a planner but fall short for an assessor.
• Your existing FRA is more than five years old. BREEAM expects updated evidence at Design Stage where an assessment has aged past five years, so an older report may need refreshing before it can be relied on.

Under current guidance, BREEAM Version 6.1 still requires a compliant, site-specific flood risk assessment — the Environment Agency's published flood maps on their own are treated as non-compliant for credit purposes, because they describe strategic flood zones rather than the risk to a specific site. If you are weighing up whether a scheme needs an FRA at all, our guide on when you need a flood risk assessment sets out the planning triggers that usually apply in parallel.

What a BREEAM flood risk assessment looks at

A credible BREEAM FRA assesses every source of flooding that could reach the site, not just the one shown on the headline map. That breadth is part of what separates a compliant assessment from a map screenshot.

• Rivers and the sea. Fluvial and tidal risk read from the flood zone, refined with site levels and, where needed, modelled data.
• Surface water. Now the most widespread source of flooding in England, and frequently the one that falls outside the mapped flood zones entirely — our primer on the sources of flood risk explains why.
• Groundwater. Slow to rise, invisible to the standard maps and governed by geology — assessed on its own terms where the ground demands it, through our groundwater flood risk work.
• Sewers, reservoirs and artificial sources. Considered where the setting makes them relevant to the scheme.
• Climate change over the building's life. The assessment applies the Environment Agency's climate change allowances so the risk is judged over the development's lifetime, not just today.

Understanding why a site sits in a given flood zone is part of the job too. A property can be zoned on the map yet sit at lower real risk once actual ground and floor levels are taken into account. That is the point of our explainer on flood zones in England, and the reason a defended site can still show in a flood zone, as covered in why you can remain in a flood zone after defences are built. Those distinctions are exactly what an assessor is looking for the FRA to resolve.

How flood risk and drainage work together under Pol 03

Pol 03 puts flood risk and surface water in the same credit for a reason: the assessor wants them to agree. The FRA sets the flood risk baseline, the mitigation and the residual risk; the drainage strategy proves that run-off rates and volumes are controlled, that exceedance flows have somewhere safe to go, and that water quality is protected. When those two documents are written separately, by different hands, they tend to contradict each other on the detail, and the assessor notices.

The 2025 National Standards for Sustainable Drainage Systems have raised the bar on what a drainage strategy is expected to show, from the discharge hierarchy through to interception and climate resilience. We deliver the FRA and the drainage strategy as one coordinated package, from one team, so the surface water evidence an assessor sees is consistent from the first page to the last.

Why BREEAM Pol 03 flood risk credits get lost

The frustrating thing about Pol 03 is that the credits are usually lost quietly, and only surface late — at Design Stage review, or worse, at Post Construction — when they are expensive to recover. The recurring reasons are consistent:

• Relying on the published maps. Environment Agency flood maps alone are non-compliant for credit purposes; the assessor needs a site-specific assessment.
• Leaving out a flood source. An FRA silent on surface water or groundwater looks incomplete to an assessor even where rivers and sea are covered well.
• Using a stale assessment. An FRA past five years old may need updated evidence before it can support Design Stage credits.
• Letting the FRA and drainage strategy drift apart. Inconsistent run-off figures or mitigation between the two documents undermine both.
• Confusing the baseline with the mitigation. Assuming good design will earn the credits, when the pre-development classification has already set the ceiling.

What a BREEAM flood risk assessment costs

There is no fixed price for a BREEAM FRA, and any firm quoting one sight-unseen is guessing. The cost follows the work the site actually needs: how many flood sources are in play, whether the risk can be resolved from desk-based data or needs modelling, the size and complexity of the scheme, and whether we are preparing a fresh assessment or building on and updating an existing planning FRA. A site that already has a sound, recent planning FRA is usually the least expensive route to the BREEAM evidence, because much of the groundwork is done.

We quote on a fixed, tailored basis once we have seen the site, so you know the figure before committing. The drivers behind FRA pricing generally are set out in our guide on how much a flood risk assessment costs. As a rule, a very cheap, generic report is a false economy on a BREEAM job: a lost credit costs far more to recover than it saves.

How Unda delivers your BREEAM FRA

We keep the process tight and BREEAM-specific, so the report an assessor receives is the one they can score without coming back with questions.

1. Establish the pre-development classification. We assess all flood sources and fix the site's pre-development flood risk — the figure that sets your credit ceiling — as early as possible.
2. Review what you already have. Where a planning FRA exists, we check whether it meets BREEAM's requirements and supplement it rather than start from scratch.
3. Align the drainage evidence. We coordinate the FRA with the surface water drainage strategy so the run-off and water-quality case is consistent.
4. Assess for the building's lifetime. The Environment Agency's climate change allowances are applied so the risk is judged over the development's life, not just at completion.
5. Present it for the assessor. The report is structured and written for Pol 03 review, with the pre-development classification, sources and mitigation set out clearly.

Why choose Unda for your BREEAM Flood Risk Assessment

Flood risk and drainage are all we do, and we do them across the whole development picture — planning, BREEAM, drainage and due diligence — rather than as a bolt-on to a broader consultancy.

• 5,000+ flood risk assessments since 2014. Depth of experience across England and Wales, from single plots to strategic sites.
• CIWEM-qualified consultants. Chartered flood risk expertise, so the technical judgement behind the classification holds up to scrutiny.
• Pol 03 understood properly. We work to how the credit is actually scored — the pre-development ceiling, the five-year evidence rule, the multi-zone worst-case rule — not a generic FRA relabelled.
• One coordinated package. FRA and drainage strategy from the same team, so the evidence agrees with itself.
• Local knowledge, everywhere. We bring catchment and council-specific insight through our area, river and local authority guides.

You can screen a site yourself before you get in touch, using our free flood risk map and postcode checker and live river levels map, though neither replaces the site-specific assessment a BREEAM submission needs.

BREEAM Flood Risk Assessment FAQs

To talk a scheme through, call us on +44 (0) 1293 214444 or email enquiries@unda.co.uk and ask for Jackie Stone, who can arrange a free, no-obligation quote tailored to your site and your target BREEAM rating.