Planning Appeals 2026: Why Flood Risk and Drainage Must Be Right First Time

A planning appeal on flood risk grounds is now, in most cases, decided on the evidence that was already sitting in the application file. Since 1 April 2026 most appeals in England run through a streamlined written representations procedure, and the Planning Inspectorate will generally consider only what the council had in front of it when it refused. Five months in, the Inspectorate's own figures show what that means in practice: the route almost every appellant is now placed on is also the route on which appeals succeed least often.

Written representations accounted for 93% of the 19,617 appeal decisions issued in the year to March 2026 — and just 30% of Section 78 appeals decided that way were allowed, against 72% at inquiry.

That gap is not evidence that inspectors treat written cases carelessly. It mostly reflects which cases go down which route, and we come back to that below. What it does tell an applicant is something blunt about the odds, and the odds land differently now the written route is the default and the evidence base closes at determination. For flood risk and drainage the change bites hardest, because an objection on either has always been answered with a better document. That option has gone. If your site sits in Flood Zone 2 or 3, the practical response is to commission a flood risk assessment for planning that is finished at the point of submission, rather than one you plan to strengthen later.

What changed in the planning appeals process on 1 April 2026?

The standard route for most refused applications became a faster, document-only written procedure, and new evidence was largely shut out. The reforms are set out in the Town and Country Planning (Appeals) (Written Representations Procedure) (England) (Amendment and Saving Provision) Regulations 2026 (SI 2026/122), which amend the principal 2009 written representations regulations and are summarised in the accompanying explanatory memorandum. They are explained in the Planning Inspectorate's procedural guide, first published in February 2026 and updated on 16 July 2026. They apply to Section 78 appeals against decisions on applications dated on or after 1 April 2026, so they phase in as those applications work through the system.

• Written representations by default. Most appeals now begin under the expedited Part 1 written procedure, which the guide describes as the simplest and quickest route. The Inspectorate can still escalate to a hearing or inquiry, but that is the exception.
• The evidence base is fixed at application stage. Inspectors primarily consider the material that was before the Local Planning Authority when it decided. Technical reports produced for the appeal are generally not accepted.
• Little room for scheme changes. Amended drawings, revised layouts or reworked mitigation fall outside the standard written procedure. The route for a changed scheme is a fresh application.
• Third parties lose their appeal-stage voice. Under Part 1 there is no opportunity for interested people to submit comments at appeal, so representations made during the application are all the Inspector sees.
• Tighter deadlines. Householder and minor commercial appeals must be lodged within 12 weeks of the decision notice, other appeals within six months, and the council returns its questionnaire within five working days of the start date.

The Inspectorate picks the procedure as soon as practicable after a valid appeal arrives, and keeps that choice under review. Either party can ask a senior officer to look at it again, and the planning practice guidance on appeals sets out how the procedures compare. But nobody should mistake the direction of travel. Announcing the change, the government put it plainly: "the majority of written representation appeals will accept only the evidence put before the local planning authority during application." Read that as a design intention rather than a side effect. The appeal was never meant to be a second bite, and from April it stopped working like one.

What can the Planning Inspectorate consider at appeal?

Under the Part 1 procedure the Inspector examines a closed set of documents: the original application and its supporting evidence, the officer report and committee minutes, the decision notice and its reasons, the appeal form, and the council's questionnaire. An appellant cannot add a stronger flood risk assessment or a revised drainage strategy at appeal to cure the reason for refusal. The guidance is explicit that the appellant is not able to submit evidence at appeal that the council did not consider when it determined the application.

This reads differently for technical disciplines than it does for a design or amenity argument, which can be made in writing from drawings the council already has. A flood risk or drainage objection is answered with a document, and that document now has to exist, and be right, before the council decides.

How often do written representations appeals actually succeed?

Around three in ten. The Planning Inspectorate's statistical release for the year to March 2026 records 9,476 Section 78 appeals decided and 19,617 decisions across all appeal types, of which 18,209 went by written representations, so the expedited route was already carrying the overwhelming majority of the caseload before the reforms formally made it the default. Of the Section 78 appeals decided between January and March 2026, 32% were allowed overall. Split that figure by procedure and it stops looking like one number.

Writing on 19 August 2026, Claire Sherratt, an Inspector Profession Lead at the Planning Inspectorate, took the gap on directly. Her argument is that procedure follows complexity rather than the other way round. Written representations carry the simpler cases, inquiries the ones that need evidence tested under cross-examination, and decision quality is held to the same standard across all three. That is a fair reading of the data, and it is worth accepting rather than arguing with. Her advice to applicants is the part worth pinning above the desk.

The Inspectorate's own advice to applicants is to submit the best available evidence at the application stage.

Both things can be true at once. The procedures are not unequal in rigour, and an applicant on the written route still faces materially worse odds than one at inquiry — on a route they no longer choose, with an evidence base they can no longer add to. In our experience the cases that fall into that trap are rarely bad schemes. They are decent schemes with a thin report. That is why the quality of a submitted flood risk assessment or surface water drainage strategy now carries weight it simply did not carry in 2025.

What counts as a "material change in circumstance"?

Four narrow categories, none of which is designed to rescue an evidence gap that existed all along. If something material has genuinely changed since the council's decision, the Inspectorate may accept new evidence, but the guide warns it is unlikely to accept new evidence relating to circumstances other than those listed. The exceptions are about the world moving on, not about an applicant catching up.

Note what is absent from that list: having now commissioned the modelling that should have been done first time. Finishing technical work after refusal is not a material change in circumstance.

Has the August 2026 NPPF reopened the door?

Partly, and only for a narrow group. A new National Planning Policy Framework took effect on 17 August 2026 and applies to every planning decision made from that date. It is the biggest restructuring of flood risk policy in the NPPF in years. A material change to national planning policy is the first of the four exception categories, so for an application refused before 17 August and appealed after it, the new Framework is capable of being a genuine material change in circumstance rather than an argument dressed up as one.

The August 2026 NPPF moves flood risk into a dedicated Chapter 18 with nine coded policies, F1 to F9, and relocates the flood zone definitions and vulnerability classification into a new Annex F.

Whether that helps depends entirely on the refusal. The exception bites only where the policy change is itself decisive, so the question to ask is narrow and specific.

• Does the new policy change the test your scheme failed? The sequential test under Policy F5 now caps the area of search to the development's likely catchment, exempts sites already sequentially tested through the local plan, and introduces a surface water sequential test exemption for surface-water-only sites. A refusal that turned on a search area the council drew too widely is a different proposition under F5.
• Was the refusal reason a drainage standard that has since changed? Policy F8 makes design to the National Standards for Sustainable Drainage Systems mandatory, and extends SuDS design and maintenance requirements beyond major development to every scheme.
• Has the wording hardened against you rather than for you? The new Framework shifts from permissive "should only be allowed" language to refusal-worded "should be refused unless" throughout, so a policy change can cut both ways.
• Are you simply citing new paragraph numbers? A report referencing the old December 2024 paragraph numbers is not wrong in substance, but renumbering is not a change in circumstance. Our guide to the August 2026 NPPF changes for flood risk and drainage maps where each old paragraph now sits, and the vulnerability classification has moved with it.

The honest position is that this is a real opening, but a narrow and temporary one, and it will close as the pool of pre-17-August refusals works its way through the system over the next few months. Where it applies, say plainly in the appeal that you are submitting new evidence, identify which exception you are relying on, and show why the policy change is decisive rather than merely relevant. Where it does not apply, it is no substitute for having evidenced the case properly the first time. Most schemes will fall into the second group.

Why do flood risk and drainage decide so many of these appeals?

Because they are, disproportionately, where applications are found wanting, and because they are the kind of objection that used to be settled with a better report at appeal. Flood risk and surface water drainage are technical, evidence-led judgements, which means that when an application is thin on either the refusal reason points squarely at a missing or inadequate document rather than at a matter of planning taste, and under the new rules that document can no longer be produced late. The refusal names the gap. The appeal cannot fill it.

In 2024/25, 96% of English planning decisions complied with Environment Agency flood risk advice, rising to 99% for proposed new homes.

A consultee position that decisive, sitting in front of an appeal route that will not look at new evidence, leaves almost no slack. A site in Flood Zone 2 or 3, or one flagged on the Flood Map for Planning, which you can check directly on the Environment Agency service, needs a complete, policy-compliant flood risk assessment in the application itself, and the Environment Agency's standing advice sets out the floor it has to clear. An Environment Agency objection on flood risk is now materially harder to overturn, because the usual way of answering one — new modelling, or a revised assessment produced at appeal — is precisely what the written procedure keeps out. An LLFA objection on drainage works the same way. Both are worth resolving during determination, while you still can.

Can sequential and exception tests still be reworked at appeal?

Not in the way they sometimes were. The sequential and exception tests turn on evidence assembled before determination: the alternative sites considered, the search area, and the flood risk information sitting behind both. If that case is not properly made at application stage, the appeal offers very little room to build it retrospectively, because the material an inspector would need to test an alternative-sites argument is exactly the material the written procedure excludes.

Appeal decisions still turn on the planning balance, and a failed sequential test is not always fatal. The Yatton appeal shows inspectors weighing flood risk against wider benefits, a reading confirmed by the Yatton judgment on the planning balance, and the Faversham appeal shifted where the bar sits on search-area evidence. But both are cases where the evidence was on the file. A properly reasoned sequential and exception test submitted with the application is now doing double duty: winning the decision, and protecting the appeal if it comes. The September 2025 PPG update had already tightened what that evidence has to show; the exception test under Policy F6 now carries a third limb on wider sustainability benefits.

What do drainage strategies need to show at submission?

Enough for the Lead Local Flood Authority and the planning officer to accept it at the point it goes in, rather than after a refusal. Lead Local Flood Authorities are statutory consultees on surface water drainage for major development, and the way LPAs assess flood risk and SuDS leaves little tolerance for a strategy that is light on design justification.

• Policy compliance. The strategy should demonstrate the drainage hierarchy has been followed and the discharge rates justified against the right standards, now mandatory under Policy F8.
• Site-specific evidence. Ground conditions, infiltration testing to BRE Digest 365 where relevant, and levels need to support the design rather than sit as assumptions.
• Enough detail to condition. Officers need a strategy they can reasonably attach a drainage condition to, not a placeholder that leaves the principle of drainage unresolved, and one you can later discharge without redesigning the scheme.
• Exceedance and climate change. Exceedance routing for events beyond the design standard, and the correct climate change allowance, are among the most common gaps an LLFA objection cites.

Where a strategy is missing or too thin to validate, the application can stall before it is even determined. Our guide to the flood risk and drainage documents that get applications invalidated covers that failure mode in detail, and if you are unsure whether your scheme needs one document or both an FRA and a drainage strategy, settle that before you submit rather than after.

Refused on flood risk or drainage — do you appeal or resubmit?

If the reason for refusal is a genuine evidence gap, a fresh application is usually the faster and safer route, because the appeal will not let you fill it. The exception is where something material has genuinely changed since the decision, which since 17 August 2026 includes the new Framework for refusals that predate it. The logic below sets out the route.

Resubmitting is not a defeat. A fresh application with the flood risk and drainage work done to standard is often quicker to a positive outcome than an appeal that is procedurally barred from considering the very evidence that would win it, and the median written representations appeal took 20 weeks to decide in the year to March 2026, against 18 weeks for planning casework overall. If you do appeal, the government's guidance on appealing a planning decision sets out the forms and the deadlines.

What does an "appeal-ready" application look like?

One built to stand on its own, so that if it is refused the appeal has real prospects on the papers already in the file. For flood risk and drainage that comes down to a short, practical sequence.

1. Screen the site early. Establish flood zone, surface water risk and any critical drainage constraints before the layout is fixed, using the Environment Agency's long-term flood risk service as a first pass, so risk shapes the scheme rather than fighting it.
2. Commission the flood risk assessment up front. A complete, policy-compliant FRA at submission, written to the new Chapter 18 policies and the planning practice guidance on flood risk and coastal change, not a screening note to be upgraded later.
3. Evidence the sequential and exception tests properly. Document the alternative sites, the search area and the reasoning so the case is on the file from the start.
4. Submit a drainage strategy the LLFA can accept. Drainage hierarchy followed, discharge rates justified, ground conditions tested where needed.
5. Engage the consultees before you submit. Resolve likely Environment Agency and LLFA concerns while you can still change the evidence, not after refusal.

Get in touch with Unda if you want flood risk and drainage evidence built to survive first contact with the council, whether that is a flood risk assessment for planning, a sequential and exception test report, or a surface water drainage strategy from our drainage strategy team. Under the 2026 rules that early investment is what protects the whole application.

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