NPPF Update August 2026: What Changed for Flood Risk and Drainage?

A new National Planning Policy Framework was published on 17 August 2026, replacing the December 2024 version. For property owners, developers and planning professionals, some of the most important practical changes concern how planning applications are assessed, when flood-risk evidence may be needed, how the Sequential Test is applied and what is expected from Sustainable Drainage Systems (SuDS).

Key Takeaways

What Changed in the 17 August 2026 NPPF?

The Government published a new National Planning Policy Framework (NPPF) on 17 August 2026, replacing the December 2024 version.

For property owners, developers and planning professionals, some of the most important practical changes concern how planning applications are assessed, when flood-risk evidence may be needed, how the Sequential Test is applied and what is expected from Sustainable Drainage Systems (SuDS).

The new Framework also introduces a clearer distinction between policies used to prepare development plans and policies used when deciding individual planning applications.

For flood-risk and drainage work, this creates a more defined set of national tests that applicants and consultants can address directly in supporting reports.

What Is the NPPF?

The National Planning Policy Framework sets out the Government's planning policies for England.

It guides both:

• the preparation of development plans; and
• decisions on planning applications and other development proposals.

Local plans still remain important. Planning applications continue to be determined in accordance with the development plan unless material considerations indicate otherwise.

The NPPF is one of those important material considerations.

Why Does the August 2026 NPPF Update Matter for Planning Applications?

One of the biggest structural changes is the clearer separation between plan-making policies and national decision-making policies.

For example:

• Policy DM1 ("Preparing development proposals") deals with how development proposals should be prepared.
• Policy DM2 ("Information requirements") covers the supporting information required to determine applications.
• Policy S4 ("Principle of development within settlements") addresses development inside settlements.
• Policy S5 ("Principle of development outside settlements") addresses development outside settlements.

This makes it easier to identify which national policies are intended to be applied directly when a planning application is being considered.

The new NPPF became a material consideration for planning decisions from 17 August 2026.

Older local planning policies do not automatically become irrelevant simply because they pre-date the new Framework. However, where an existing development-plan policy is materially inconsistent with a new national decision-making policy, the NPPF states that it should generally be given very limited weight, subject to the exceptions in the Framework.

For applicants, this makes it important to use the current NPPF when preparing or reviewing planning evidence.

Does the New NPPF Change Flood Risk Assessment Requirements?

Yes, in relevant circumstances.

Compared with the previous policy approach, the August 2026 wording broadens the circumstances in which a site-specific Flood Risk Assessment (FRA) may be required where a site is identified as being at flood risk.

This makes it particularly important not to assess flood risk solely by looking at whether a property falls within Flood Zone 1, 2 or 3.

Flood Zones primarily relate to river and sea flooding. Depending on the site, other sources may also be relevant, including surface-water flooding and future flood risk.

A site in Flood Zone 1 should therefore not automatically be treated as a site where no further flood-risk assessment could be needed.

That does not mean every development in Flood Zone 1 now requires an FRA. The requirement and level of assessment will depend on the actual site, development proposal and applicable planning requirements.

How Is Flood Risk Organised in the New NPPF?

Flood risk and coastal change are now covered through policies F1 to F9.

For individual development proposals, some of the most important are:

This provides a useful structure for preparing an FRA or reviewing the flood-risk position of a development.

In practical terms, the process may involve establishing:

1. whether the Sequential Test applies;
2. whether the Exception Test is required;
3. whether the development will remain safe for its lifetime; and
4. how surface-water drainage will be managed.

The exact requirements depend on the proposal.

Has the August 2026 NPPF Changed the Sequential Test?

Yes. Policy F5 ("Applying the sequential test") clarifies when the Sequential Test is required, including an important provision for sites affected only by surface-water flooding.

The Sequential Test is used to help steer development towards areas with a lower probability of flooding where appropriate.

Under the new policy, where a site is at risk solely from surface-water flooding, the Sequential Test does not need to be applied in the specified circumstances where the proposed layout, design and mitigation can demonstrate that:

• occupiers and users will remain safe from current and future surface-water flood risk throughout the development's lifetime; and
• the development will not increase flood risk elsewhere.

This distinction is important.

It does not mean that surface-water flood risk can simply be ignored.

Surface-water flooding still needs to be assessed and appropriately managed. The change relates specifically to whether the Sequential Test itself is required.

Policy F5 also identifies certain development types for which the Sequential Test is not required, including specified householder development, small non-residential extensions and certain changes of use.

Applicants should therefore establish the Sequential Test position from the characteristics of the individual proposal rather than relying on a general assumption.

When Does the Exception Test Apply?

Policy F6 ("Development in areas at risk of flooding from rivers or the sea") addresses development in Flood Zones 2, 3a and 3b.

Where the Exception Test is required, the proposal needs to demonstrate that:

• the development provides wider sustainability benefits that outweigh the flood risk;
• it will be safe for its anticipated lifetime; and
• it will not increase flood risk elsewhere and, where possible, will reduce overall flood risk.

A site-specific Flood Risk Assessment is used to inform the Exception Test where required..

Not every development in Flood Zones 2 or 3 is treated in exactly the same way. The proposed use, flood vulnerability and individual circumstances all matter.

What Does Policy F7 Mean for Development Safety?

Policy F7 ("Ensuring development is safe from flooding") sets out the safety requirements for proposals in locations known to be at risk from flooding, now or in the future.

Where relevant, a development may need to demonstrate:

• that more vulnerable parts of the development are placed in areas of lower flood risk within the site;
• that people can remain safe throughout the development's lifetime;
• that residual flood risk can be safely managed;
• that safe access and escape are provided where appropriate;
• that suitable flood resistance and resilience measures are incorporated; and
• that the proposal will not increase flood risk elsewhere.

This is why an effective FRA should do more than state a site's Flood Zone.

Where risk exists, it should explain what the risk means for the proposed development and how that risk will be managed.

What Does Policy F8 Mean for SuDS and Drainage Strategies?

Policy F8 ("Sustainable drainage systems and watercourses") is particularly important for developers preparing drainage information.

Where a development could affect drainage on or around the site, the policy says Sustainable Drainage Systems should be incorporated proportionately to control surface-water flow rates and reduce runoff volumes.

Where possible, SuDS should also provide wider benefits, including:

• improved water quality;
• biodiversity; and
• amenity.

The policy states that SuDS should be designed in accordance with the National Standards for Sustainable Drainage Systems..

It also requires maintenance arrangements to be in place so the system can continue operating to an acceptable standard throughout the anticipated lifetime of the development.

For major development, advice from the Lead Local Flood Authority (LLFA) should also be taken into account.

What Should a Drainage Strategy Now Demonstrate?

For applicants, a drainage strategy should increasingly explain more than simply where surface water will discharge.

Depending on the development, it may need to show:

• how surface-water runoff rates will be controlled;
• how runoff volumes will be managed;
• how the proposed SuDS approach responds to the National Standards;
• how water quality and other multifunctional benefits have been considered;
• who will maintain the drainage system; and
• how it will continue to operate over the development's lifetime.

Considering these issues before the site layout is fixed can be valuable because SuDS features and atenuation storage can require significant space.

What Does the NPPF Say About Watercourses and Culverts?

Policy F8 also addresses existing watercourses.

New development should generally avoid enclosing an existing open watercourse within a culvert unless there are compelling reasons to do so.

Where possible, opportunities to remove existing culverts and restore more natural river channels should also be considered, provided this would not increase flood risk or create other unacceptable environmental or heritage impacts.

For sites containing a stream, ditch, ordinary watercourse or culvert, this can therefore be an important early design consideration.

Are There New National SuDS Templates?

Yes, but the templates are separate from the NPPF itself.

On 18 August 2026, the Chief Planner announced national SuDS Strategy Templates for Major and Non-major Development.

The templates were developed through an Environment Agency-led working group and are intended to help applicant submit drainage information in a more consistent way and support assessment against the National SuDS Standards.

They should be treated as supporting implementation guidance, rather than additional NPPF policy.

The August 2026 NPPF also did not itself bring Schedule 3 of the Flood and Water Management Act into force. The Government indicated that this remains a separate matter.

Why Are Early Flood-Risk and Drainage Checks Important?

The new NPPF does not require every landowner to commission a detailed Flood Risk Assessment or Drainage Strategy at the start of a project.

However, early checks can help identify issues that may affect whether a proposal is practical and how the site should be designed.

Early review can be particularly useful where:

• the site has mapped river, sea or surface-water flood risk;
• a watercourse or culvert crosses the site;
• drainage discharge options are uncertain;
• the proposal is in Flood Zone 2 or 3;
• a Sequential Test may be required; or
• the development could significantly change surface-water runoff.

Flood risk and drainage can influence site layout, access arrangements, finished floor levels, development capacity and the amount of land required for SuDS.

Identifying these constraints before a design is advanced can reduce the risk of significant redesign later.

Who May Be Affected by the NPPF Update?

Will Existing Planning Applications Be Affected?

Potentially, yes.

The new national decision-making policies became material considerations on 17 August 2026.

A planning application submitted before that date but still awaiting determination may therefore need to be considered against the updated NPPF.

This does not mean that every live application automatically needs a new Flood Risk Assessment or revised Drainage Strategy.

However, it is sensible to check whether the new national policies materially affect the evidence already submitted.

What Should Applicants Do Now?

Before submitting or progressing a planning application:

• Review the proposal against the 17 August 2026 NPPF.
• Check flood risk from all relevant sources, rather than relying only on river and sea Flood Zones.
• Confirm whether a Flood Risk Assessment is required.
• Establish the Sequential Test and Exception Test position, where relevant.
• Assess drainage and SuDS feasibility before fixing the site layout.
• Check the National SuDS Standards, maintenance requirements and any watercourses or culverts.
• Review local validation requirements and any technical reports already submitted.

Not every project will require every step. The appropriate level of assessment should remain proportionate to the site and proposed development.

Frequently Asked Questions

What Should Property Owners and Developers Take from the Update?

The NPPF update August 2026 gives flood risk, development safety and sustainable drainage a clearer set of national policy tests.

For most applicants, the practical priority is not simply learning the new policy numbers. It is understanding whether those policies change what needs to be assessed for a particular site.

Checking flood risk, the Sequential Test position and drainage feasibility early can help identify constraints before the planning submission or design becomes too advanced.

If a development may be affected by the updated policy, RIDA Reports can review the site's Flood Risk Assessment, drainage strategy, SuDS or Sequential Test requirements before submission, or assess whether existing technical information may need updating.

The requirements depend on the individual site, development proposal and planning context. Technical assessment cannot guarantee planning permission, but it can help ensure that the relevant flood-risk and drainage issues are identified and addressed appropriately.

Recommended Authoritative Sources

• National Planning Policy Framework – August 2026 – Ministry of Housing, Communities and Local Government / GOV.UK
• Government response to the National Planning Policy Framework consultation – August 2026 – GOV.UK
• Chief Planner Newsletter – August 2026 – GOV.UK
• National Standards for Sustainable Drainage Systems – GOV.UK

The NPPF should be treated as the primary source for final policy. The consultation response explains how the final position developed, while the Chief Planner material and SuDS templates provide supporting implementation guidance.