What Is a Strategic Flood Risk Assessment (SFRA)?

A strategic flood risk assessment (SFRA) is the flood risk evidence base a local planning authority produces for its whole area, covering every source of flooding, now and under climate change. Every local planning authority in England has to prepare one. It is not a document you commission, and it is not policy in its own right. It is the evidence councils use to decide where development goes, and the evidence you are expected to have read before you submit.

Almost everything published about SFRAs is written for the councils producing them. This article is written for the other side of the desk: what the SFRA says about your site, where to find it, and what a case officer will expect you to have done with it.

Since 17 August 2026 the requirement has sat at Policy F1 of the National Planning Policy Framework, inside a new Chapter 18. The old paragraph 171 no longer exists as national policy.

What is a strategic flood risk assessment?

SFRA meaning: SFRA stands for strategic flood risk assessment. If a planning officer has told you to check the SFRA, the question what is an SFRA has a short answer: it is your council's own area-wide flood risk study, and it already says something about your site.

A strategic flood risk assessment is a study prepared by a local planning authority that maps and describes flood risk across its area from every source: rivers, the sea, surface water, groundwater, sewers and reservoirs, taking account of climate change and the cumulative effect of development. It underpins the local plan, and it tells applicants which sites carry which constraints before anyone designs anything.

The word doing the work is strategic. An SFRA looks at a district, a borough or a group of authorities as a whole, drawn at the scale of a plan rather than a plot, and its purpose is to let the council steer growth towards the land that floods least rather than to tell any individual applicant what to build.

That scale is also its limit. An SFRA will tell you the site sits under a mapped surface water flow route, or that the council treats a particular watercourse corridor as functional floodplain, but it will not tell you what finished floor level your building needs or where on the plot you can safely put the front door. That is the job of a site-specific flood risk assessment. The two documents are related without being interchangeable.

• Maps every flood source. Rivers and the sea, but also surface water, groundwater, sewers, reservoirs and coastal erosion, none of which the national Flood Map for Planning brings together in one place.
• Applies climate change. It carries the allowances current for that area, so the plan is tested against future risk rather than today's.
• Defines the functional floodplain. Flood Zone 3b is set locally through the SFRA. It is not published nationally.
• Supports the sequential test. It gives the council a defensible ranking of land by flood risk at plan-making stage.
• Identifies land for flood management. Space needed for defences, storage or natural flood management is safeguarded through the plan.
• Flags where an assessment will be needed. Including the parts of Flood Zone 1 where a site-specific assessment is still required.

An SFRA is evidence. It is not policy, and that distinction settles arguments. A local plan policy can be applied to refuse an application; an SFRA cannot, because it carries no policy status of its own. It is tested instead at examination of the plan, where an inadequate evidence base is a soundness problem rather than a development management one. What it does is supply the factual basis a policy is applied through. In practice that means an officer leans on it heavily, and an application that ignores it reads as unevidenced.

Who produces an SFRA, and what does the NPPF require?

Every local planning authority in England must prepare a strategic flood risk assessment for its area. Since 17 August 2026 that requirement has sat in Policy F1 of the National Planning Policy Framework, within a new Chapter 18 on flood risk and coastal change. Councils normally commission the technical work from consultants, and often prepare a joint SFRA with neighbouring authorities where catchments cross administrative boundaries.

The August 2026 Framework reorganised flood policy substantially. What used to be a run of paragraphs inside Chapter 14 is now nine coded policies, F1 to F9, with the flood zone thresholds and the vulnerability classification moved into a new Annex F. Paragraph 171, the old SFRA requirement, became Policy F1. The sequential and exception tests the SFRA feeds became Policies F5 and F6. Our guide to the August 2026 NPPF flood and drainage changes maps each old paragraph to its replacement, and our NPPF flood risk guidance sets out what the Framework now asks an application to submit.

The renumbering matters more than it sounds. A report citing December 2024 paragraph numbers is not wrong in substance, but the officer reading it is working from the F codes, and since April 2026 the appeal rules leave far less room to repair weak evidence after a decision. If you need a flood risk assessment written to the current Framework, it needs to cite Chapter 18 and Annex F rather than the paragraphs most published guidance still quotes.

There is a trap here worth knowing about. The GOV.UK guidance on preparing an SFRA was updated on 27 August 2026 and reflects the new Framework. The Planning Practice Guidance on flood risk and coastal change, which sits beside it and which a great deal of published advice still works from, was last updated on 17 September 2025. It still cites paragraph 167 and Annex 3, and makes no mention of Chapter 18 or the F policies anywhere. Two government pages, two vintages of policy. Where they diverge, cite the Framework itself.

Two GOV.UK pages currently describe the same policy area a year apart. The SFRA guidance was updated in August 2026; the Planning Practice Guidance behind it has not moved since September 2025.

What is actually inside a strategic flood risk assessment?

An SFRA arrives in parts rather than as a single report: a main report explaining method and findings, a set of GIS layers or a map atlas, appendices holding the source data and modelling, and increasingly a site pro-forma summarising the constraints on each allocated site. The maps are usually what you want. The report tells you how they were made, and that is what you need on the day you have to argue with them.

Government guidance is specific about what the mapping has to show: all flood risk sources, past flooding, flood warning and alert areas, flood risk management features and structures, land needed for future flood management infrastructure, the functional floodplain designation, and the areas affected by climate change. The supporting report should set out the flood sources, the defences, reservoir risk, cumulative development effects, and (the line applicants most often need) the areas of Flood Zone 1 where a sequential test and a flood risk assessment will still be required.

The underlying data comes from published national sources: the Flood Map for Planning, Environment Agency datasets on the Defra Data Services Platform, British Geological Survey groundwater susceptibility mapping, coastal erosion data, and the council's own section 19 flood investigation reports and water company records. Very little of it is secret. What the SFRA adds is local interpretation, and a judgement about what those datasets mean on this particular ground. The SFRA good practice guide published by ADEPT and the Environment Agency remains the fullest account of how that interpretation is meant to be done, though it dates from 2021 and predates both the current mapping and the current Framework.

Level 1 or Level 2: which SFRA does your council have?

A Level 1 SFRA is the baseline every local planning authority produces, a strategic overview of flood risk across the whole area, assembled largely from existing data. A Level 2 goes further and models specific sites in detail. It is only needed where the council cannot allocate all its development outside flood risk areas, or where it can but expects a high volume of applications on land that is at risk.

That trigger is the part most guidance skips over. The council decides, informed by its own Level 1 findings and by consultation with the Environment Agency and its lead local flood authority. Where the Level 1 shows the housing requirement can be met on low-risk land, no Level 2 follows. Where it cannot, which is routine in a tightly constrained district, the Level 2 supplies the evidence needed to apply the exception test at allocation stage.

A Level 2 is a different kind of document, not a longer one. Where a Level 1 tells you a site is in Flood Zone 3a, a Level 2 should tell you how deep the water gets, how fast it arrives, how long it stays, what happens if a defence breaches, and whether people could leave safely. Breach modelling, hazard rating, depth and velocity, speed of onset and access and egress analysis all belong at Level 2, and the guidance sets out each of them as content a Level 2 should carry. Where the Level 2 does the work well, it also shapes the standing advice a council applies to smaller schemes.

In practice the two levels blur. Often badly. Many authorities now publish a combined or hybrid SFRA carrying Level 2 detail for allocated sites inside a Level 1 that covers everything else, and update it in rolling instalments rather than as a single reissue. If you are hunting for a document called "Level 2 SFRA" and cannot find one, check whether the Level 1 has site appendices doing the same job under another name.

Why the SFRA, not the flood map, defines Flood Zone 3b

Flood Zone 3b, the functional floodplain, does not appear on the Environment Agency's Flood Map for Planning. It is defined locally, through the SFRA, authority by authority. If you need to know whether a site is in 3b, the national map will not tell you and the SFRA is the only place to look.

This catches people out, and it costs schemes. It is probably the single most consequential thing the national mapping does not show, because a designation that rules out most forms of development is made locally, published locally, and easy to miss if you have only looked at the map everyone knows about. The national map shows Flood Zones 1, 2 and 3, with Zone 3 undivided. The split between 3a and 3b is a local judgement, and a consequential one, because most development is unacceptable in the functional floodplain however well it is designed.

Government guidance sets the starting point as land flooding from rivers or the sea with a 1 in 30 (3.3%) annual probability, with defences operating as designed, plus existing river channels and any land engineered to flood, such as an attenuation scheme. Councils are told not to fold surface water into the designation, and to assess future climate change effects separately rather than build them into the 3b line itself.

The guidance leaves room, though, and authorities use it differently. Some run the 1 in 30 as published. Others adopt a more precautionary extent, or map a separate climate-change functional floodplain alongside the present-day one so that land which is not functional floodplain today is treated as constrained for the purposes of a scheme with a hundred-year design life. There is no way to work out which approach applies other than reading the SFRA that covers the site.

Two adjoining boroughs can designate the same stretch of river corridor differently. Nothing on the national map will tell you which one you are dealing with.

SFRA or site-specific flood risk assessment: what is the difference?

An SFRA is prepared by the council for its whole area and is not site-specific. A flood risk assessment is prepared by the applicant, for one site and one proposal. The SFRA is an input to your assessment, never a substitute for it, and planning guidance is explicit that a site-specific assessment should make optimum use of information already available, including the SFRA.

The relationship runs one way. Your assessment should reference the SFRA, adopt its functional floodplain designation, use its climate change position, and explain any departure from it. An assessment reaching a different conclusion from the SFRA without saying why invites an objection, and objections from the Environment Agency or the lead local flood authority are what stall determinations. Where a site needs both, our flood risk assessment for planning and sequential and exception test reports are prepared together so the two documents agree with each other and with the SFRA.

How to find your council's strategic flood risk assessment

SFRAs are almost never filed under flooding. They sit in the local plan evidence base, because that is what they are — evidence supporting a plan. Search the council's planning policy pages rather than its drainage or emergency pages, and expect a report plus a separate set of maps rather than one file.

1. Identify the right authority. The SFRA belongs to the body that determines planning applications. In a two-tier area that is the district or borough, not the county council acting as lead local flood authority.
2. Go to planning policy, not flooding. Look for "local plan evidence base", "planning policy evidence", "local plan background documents" or "examination library". That is where it lives.
3. Search the site for "SFRA". The acronym returns better results than the full phrase on most council search functions, because that is what the filenames use.
4. Take the maps as well as the report. The report is the smaller download and the less useful one. The map atlas or GIS viewer is where your site's constraints are.
5. Check for a Level 2 or site appendices. If the site is allocated, look for a pro-forma or appendix covering it specifically before reading the general chapters.
6. Note the date and the data vintage. Both the publication date and the datasets it was built from. You will need them later if the SFRA and current Environment Agency data disagree.

Two practical warnings. Several authorities have moved the SFRA onto a standalone interactive portal rather than publishing PDFs. the West London sub-regional SFRA is the best-known example, and some councils, such as East Riding of Yorkshire and the Royal Borough of Kensington and Chelsea, publish theirs as a set of separately dated volumes. If the planning policy page offers only a summary, look for a link out.

Where an SFRA covers several authorities jointly, the same document may appear on each partner's website at different versions. Take the most recent, and note which authority published it. Our local planning authority guides set out how individual councils handle flood risk and drainage evidence, and the free flood risk map checker will give you a postcode-level starting point before you open anything.

How to use the SFRA on a planning application

Read the SFRA before you design the scheme. Not after the officer asks for it. It settles three things early enough to matter: whether the site is treated as functional floodplain, which flood sources the council expects to see assessed, and whether an assessment and a sequential test will be required at all. Each of those changes what you submit and what the scheme can be.

• Check the functional floodplain first. If the SFRA puts the site in Flood Zone 3b, the layout question comes before the mitigation question. Most uses are unacceptable there whatever the design.
• Take the sequential test trigger from it. The SFRA identifies the Flood Zone 1 land where a test is still expected, including land at surface water risk under Policy F5.
• Look for a critical drainage designation. Many councils designate critical drainage areas through the SFRA or a surface water management plan, and the designation only binds through local policy and the validation list.
• Adopt its climate change position. Using a different allowance from the one the SFRA applies is a legitimate choice, but only an explained one.
• Cite it directly in the assessment. Name the SFRA, its version and its date. An officer who can see you have read it reads the rest differently.
• Carry it into the sequential test statement. The SFRA's ranking of land by flood risk is the council's own evidence, and the strongest material available for an area of search argument.

The commonest failure is treating the SFRA as background reading and citing it once, in a paragraph nobody reaches. It works far better as the spine of the evidence: the SFRA identifies the constraint, your assessment quantifies it at site scale, and the design responds to it. An officer following that thread has something they can approve.

What if the SFRA is out of date or contradicts the flood map?

An out-of-date SFRA does not stop being the council's adopted evidence, but it stops being the best available information, and national policy asks decision-makers to work from the best available information. Where the SFRA and current Environment Agency data disagree, say so in the assessment, explain which you have relied on and why, and be ready to defend the choice.

This is a live problem, not a theoretical one, and it has become sharper over the last eighteen months than at any point since the flood zones were first published. The Environment Agency rebuilt its national mapping as NaFRA2 in March 2025, added surface water climate change extents and banded depth data to the Flood Map for Planning in May 2026, and revised its climate change allowances more than once over the same period. A great many SFRAs predate all of it.

Reviewing takes budget and time, and plenty of authorities are behind. Some are years behind. The practical position is that neither document simply overrides the other. The SFRA carries local interpretation the national datasets do not — a defence condition, a recorded flood, a local view on functional floodplain — while the national data carries a currency the SFRA may have lost. Either way the residual risk has to be described somewhere, and it is better described by you than by a consultee. A well-argued assessment uses both, names the conflict openly, and does not leave the officer to find it.

An assessment that quietly relies on whichever of two conflicting datasets is more convenient is the kind that attracts a holding objection.

Frequently asked questions

If a strategic flood risk assessment has flagged something on your site, the next document is usually yours to produce. Unda prepares flood risk assessments for planning across England and Wales, and can tell you within an hour whether one is needed. Call 01293 214444 or email enquiries@unda.co.uk.