Planning Refused on Flood Risk Grounds: Appeal or Resubmit?
When planning permission is refused on flood risk grounds, the decision to appeal or resubmit depends on the strength of your evidence and the nature of the refusal.
A planning refusal on flood risk grounds is not the end of the road. It is, however, a fork in it. The decision you make next — whether to appeal under Section 78 of the Town and Country Planning Act 1990 or to revise and resubmit — will have significant consequences for your project timeline, cost, and chances of securing permission.
This post sets out a framework for making that decision, explains what evidence tends to succeed at appeal, and provides practical guidance on both routes.
Why Applications Are Refused on Flood Risk Grounds
Before deciding on a strategy, it is essential to understand precisely why the application was refused. Flood risk refusals typically fall into one of four categories.
Sequential Test Failure
The LPA concluded that reasonably available alternative sites exist at lower flood risk. This is one of the most common refusal reasons for sites in Flood Zones 2 and 3. The LPA may have identified specific alternative sites, or simply concluded that the applicant’s evidence was insufficient to demonstrate no alternatives exist.
Inadequate Flood Risk Assessment
The flood risk assessment was found to be deficient — perhaps it relied on outdated data, failed to consider all sources of flooding, applied incorrect climate change allowances, or did not adequately assess safe access and egress. The Environment Agency (EA) may have issued a sustained objection, which carries considerable weight with both the LPA and any subsequent appeal inspector.
Unacceptable Flood Risk to Future Occupants
Even where the FRA was broadly competent, the LPA may have concluded that the development would place future residents at unacceptable risk. This arises where flood depths or hazard ratings exceed acceptable thresholds, or where proposed mitigation was considered insufficient.
Insufficient Drainage Strategy
The Lead Local Flood Authority (LLFA) objected on the basis that the surface water drainage strategy was inadequate — failure to demonstrate greenfield runoff rates, lack of SuDS management train, no exceedance routing, missing infiltration testing, or absence of a maintenance plan.
The Decision Framework: Appeal or Resubmit?
This should be a rational assessment based on the strength of your evidence, the nature of the refusal, the scope for redesign, and the relative cost and time of each route.
When to Appeal
An appeal is the right strategy when the evidence was fundamentally sound but the decision was wrong.
The LPA misinterpreted policy or misapplied the evidence. If your FRA was robust, your Sequential Test thorough, and the EA did not object, but the LPA still refused, there may be a strong case that the decision was unreasonable. Planning inspectors take an independent view and are not bound by the LPA’s interpretation.
New data supports your case. The release of NaFRA2 (National Flood Risk Assessment 2) data has materially changed the flood risk picture for many sites. If NaFRA2 shows your site is at lower risk than the EA’s previous Flood Map for Planning indicated, this provides powerful evidence at appeal. We used NaFRA2 data to win an appeal in Petersfield where the refusal was based on superseded mapping.
The refusal reason was narrow. If the refusal relates to a specific issue — the climate change allowance applied, or the freeboard on finished floor levels — it may be possible to address this through additional evidence at appeal without redesigning the scheme.
The LPA’s Sequential Test assessment was flawed. If the LPA identified alternative sites that are not reasonably available (too small, not for sale, allocated for a different use, or at equivalent flood risk), an appeal allows you to challenge their assessment on its merits.
When to Resubmit
Resubmission is the right strategy when the evidence or the scheme was genuinely deficient.
The FRA was genuinely inadequate. If the refusal identifies legitimate deficiencies — outdated modelling, missing flood sources, incorrect climate change allowances — these need correcting. Taking a deficient FRA to appeal is unlikely to succeed and risks establishing an unhelpful precedent.
The scheme can be redesigned. If raising finished floor levels, repositioning buildings, providing compensatory storage, or redesigning the drainage strategy would overcome the refusal, resubmission is often faster and cheaper than an appeal.
The cost and time of appeal outweigh resubmission. If the deficiency can be addressed and the revised application determined within 8 to 13 weeks, resubmission is the more pragmatic route.
The EA or LLFA sustained their objection. A sustained EA objection on a matter of principle is very difficult to overcome at appeal. Inspectors give significant weight to the EA’s technical expertise.
What Evidence Wins at Appeal
If you decide to appeal, the quality of your technical evidence is paramount. The following types carry particular weight.
Updated Flood Modelling
Bespoke flood modelling that supersedes the EA’s broad-scale mapping is one of the most effective tools at appeal. If detailed hydraulic modelling demonstrates that the site is at lower risk than the Flood Map for Planning suggests, this can fundamentally change the inspector’s assessment. The modelling must meet current standards and ideally be reviewed by the EA before the hearing.
NaFRA2 Data
NaFRA2 provides a more granular assessment of flood risk than the previous mapping. Where it supports a lower risk classification, present it clearly alongside the existing EA mapping with an explanation of why the newer dataset is more reliable for the site.
Revised Sequential Test
A revised Sequential Test addressing the LPA’s specific concerns can be submitted as appeal evidence — a more thorough analysis of alternatives, evidence that identified sites are not reasonably available, or an updated search reflecting changed circumstances.
Compensatory Storage Design
Detailed compensatory storage calculations demonstrate that the development will not increase flood risk elsewhere. Level-for-level compensation within the same flood cell, supported by modelling showing no off-site increase in flood levels, is persuasive. Our retrospective pond appeal illustrates how properly designed compensatory measures resolved a difficult position.
Timeline and Cost Comparison
Appeal Timelines
- Written representations: 6 to 12 months. The most common procedure for straightforward flood risk appeals.
- Hearing: 12 to 18 months. Appropriate where issues require discussion but not formal cross-examination.
- Public inquiry: 12 months or more. Reserved for complex or significant cases; rare for flood risk-only issues.
Resubmission Timelines
- Minor/householder applications: 8 weeks statutory determination.
- Major applications: 13 weeks statutory determination.
- With pre-application engagement: Add 4 to 8 weeks for discussions with the EA, LLFA, and LPA, but this significantly improves approval prospects.
Cost Considerations
Appeal costs include the appeal statement, additional technical evidence, and potentially professional representation. For a written representations appeal with updated flood risk evidence, expect several thousand to upwards of fifteen thousand pounds depending on complexity.
Resubmission costs are generally lower: the LPA fee may be waived if resubmitted within 12 months, and the work is focused on addressing the specific deficiency. However, for a developer holding a site with financing costs, a 12-month appeal represents a significant carrying cost that may outweigh any direct savings.
The Role of the EA and LLFA at Appeal
The EA and LLFA provide written statements to the Planning Inspectorate setting out their position. If the EA sustained an objection at application stage, they will almost certainly maintain it at appeal unless new evidence addresses their concerns.
Engaging with the EA before deciding on the appeal route is therefore critical. If you can resolve their objection before the appeal is determined, their withdrawal significantly strengthens your case. Proceeding with a sustained EA objection and no new evidence is a high-risk strategy.
Section 78 Appeal Process
A Section 78 appeal is made to the Planning Inspectorate after an LPA refuses planning permission. The key steps are:
- Submission: Within 6 months of the refusal date (12 weeks for householder applications), with all supporting documents.
- Validation: The Inspectorate validates the appeal and notifies the LPA, who submit their statement of case.
- Evidence exchange: Both parties submit evidence, including the FRA, modelling reports, Sequential Test, and written statements from the EA and LLFA.
- Site visit: The inspector carries out an unaccompanied or accompanied visit.
- Decision: The inspector issues a decision letter allowing or dismissing the appeal with full reasons.
For a detailed explanation of the policy tests referenced in flood risk appeals, see our guide to the Sequential and Exception Tests.
When to Commission New Technical Work
- Refusal cited outdated data or modelling: Commission updated work. Relying on rejected evidence will not produce a different outcome.
- Policy interpretation dispute: Existing evidence may suffice, supplemented by a stronger planning argument.
- NaFRA2 or updated mapping changes the picture: A technical addendum presenting the new data may be sufficient without a full new FRA.
- Drainage strategy was objected to: Commission revised calculations, potentially with infiltration testing if that was the identified gap.
The evidence must withstand scrutiny by the inspector, the EA, and the LLFA. An appeal is not the place for shortcuts.
Getting the Evidence Right
Whether you appeal or resubmit, the quality of flood risk evidence is the determining factor. A well-evidenced case wins; an under-evidenced case loses.
At Aegaea, we prepare flood risk assessments and flood modelling evidence designed to withstand scrutiny at appeal. We have successfully supported appeals across England, providing updated modelling, revised Sequential Tests, and technical evidence that has resolved EA objections and secured planning permission.
If your application has been refused on flood risk grounds and you need advice on whether to appeal or resubmit — or need appeal-ready technical evidence — get in touch. We will review the refusal reason, assess the existing evidence, and recommend the most effective route to securing permission.