What’s changed in the sequential test for flood zone planning?

What’s changed in the sequential test for flood zone planning?

The Government has recently updated its Planning Practice Guidance (PPG) on flood risk, offering new clarity on what constitutes a “reasonably available” site.

While this may seem like a technical adjustment, it has real implications for developers and landowners in achieving planning applications in flood-prone areas.

Kiran Maher, Associate in Thrings’ Planning and Environment team, reviews the changes and explains what they mean for those looking to develop land in areas affected by flood risk.

Understanding the sequential test

The sequential test is a planning tool designed to steer development away from areas at high risk of flooding.

To pass the test and allow development to proceed at sites with high risk, applicants must demonstrate that there are no other suitable sites available which have a lower level of flood risk.

Until now, what counted as the definition of a “reasonably available” site has been open to interpretation, leading to inconsistent decision-making.

What’s changed?

The updated guidance now defines a “reasonably available” site as one that:

• Is suitable for the proposed development;
• Can be delivered within the same timeframe;
• Does not need to be owned or controlled by the applicant; and
• May consist of multiple smaller sites that collectively meet the development need.

This broader definition means planning authorities can now consider a wider range of alternative sites, even those outside the applicant’s ownership, when assessing flood risk.

Implications for developers

For developers, this change introduces a new layer of complexity. Planning authorities may now point to other sites, including those not under the developer’s control, as viable alternatives. This could delay or derail applications unless developers can provide robust evidence that no other suitable sites exist.

It also raises practical questions: how can developers assess the deliverability of sites they don’t own? How will authorities weigh the feasibility of splitting developments across multiple locations?

Implications for landowners

These changes mean that landowners with sites in flood zones may find it harder to secure planning permission, particularly if local authorities identify other “reasonably available” sites. This makes early engagement with planning consultants and legal advisors essential in order to obtain permissions.

Landowners should also be aware that the updated guidance could affect land value and development potential, especially where flood mitigation measures are required.

What you should do

To navigate the updated guidance effectively:

• Start early: Conduct thorough site assessments and flood risk evaluations before submitting applications.
• Build your case: Prepare strong evidence to support your site selection, including viability, deliverability, and setting out the planning context.
• Seek expert advice: Utilise the experiences of planning consultants and legal advisors who understand the nuances of the sequential test and flood risk policy.

Kiran Maher, Associate in Thrings’ Planning and Environment team, said: “The updated guidance brings welcome clarity to the sequential test, but it also means developers and landowners need to be more strategic in how they present their sites. It’s no longer just about ownership - it’s about suitability, timing, and deliverability.

“With careful planning and the right advice, it’s still very possible to move forward with development, even in areas affected by flood risk.”

Thrings’ Planning and Environment lawyers have extensive experience in navigating complex local and national planning policy legislation and has successfully supported commercial and residential applications through the approval and appeal processes. To find out more and for advice on your development proposals, please do get in touch.