If you are preparing a planning application in England in 2026, the drainage question has changed shape. Sustainable drainage systems — SuDS — are no longer a nice-to-have bolt-on; they are the expected way to manage surface water on almost every site. But the legal route to getting there has taken an unexpected turn. This guide sets out where SuDS and flood risk assessment stand in 2026: the new National Standards, the fate of Schedule 3, and what both mean for your application.
SuDS in one paragraph
Sustainable drainage systems manage rainfall close to where it falls, mimicking natural processes instead of piping everything straight to a sewer. Soakaways, permeable paving, rain gardens, swales, ponds and attenuation tanks all slow water down, store it, clean it and release it gradually. The aims are to cut flood risk, reduce pressure on overloaded sewers and storm overflows, and deliver water-quality, amenity and biodiversity benefits along the way. For most planning applications, a SuDS-based drainage strategy is now assessed as part of, or alongside, the flood risk assessment.
The 2026 headline: National Standards, not Schedule 3
For years the industry expected Schedule 3 of the Flood and Water Management Act 2010 to be commenced in England. Schedule 3 would have made SuDS effectively mandatory, introduced national approval bodies (SABs) and set adoption and maintenance rules. It has been in force in Wales since 2019, and its arrival in England was widely trailed.
That is not what happened. The government confirmed that Schedule 3 will not be commenced in England, judging that better outcomes can be achieved by strengthening the existing planning-led approach — improving policy, adoption and maintenance — rather than by standing up a new statutory regime. In its place, the framework now runs through the planning system, anchored by a new set of national standards.
Published by Defra as the National Standards for Sustainable Drainage Systems and updated shortly after release, these standards set out a series of design objectives that every scheme’s drainage should meet. In broad terms they cover:
- Runoff destination — discharging to the ground, then a watercourse, and only to a sewer as a last resort (the SuDS drainage hierarchy).
- Everyday and extreme rainfall — managing frequent small storms and rarer, more intense events, with climate change allowances built in.
- Water quality — treating runoff before it leaves the site.
- Amenity and biodiversity — using drainage features that also add green space and habitat.
- Lifecycle and maintenance — designing systems that can realistically be maintained for the long term.
How the planning system enforces it
Because SuDS is delivered through planning rather than a standalone consent, the pressure points are policy and validation. The NPPF already expects major development to incorporate SuDS unless there is clear evidence it would be inappropriate, and proposed policy revisions tie drainage design explicitly to the National Standards. Lead Local Flood Authorities (LLFAs) are statutory consultees on major applications and will scrutinise the drainage strategy against those standards.
The practical consequence: a vague note that “SuDS will be provided” is no longer enough. Increasingly, applicants are expected to show a designed, calculated drainage strategy — runoff rates, storage volumes, the treatment train and a maintenance plan — consistent with the standards and with CIRIA C753, the SuDS Manual.
What this means for your flood risk assessment
Surface water and drainage sit at the heart of a modern FRA. If you are unsure whether you need one at all, start with our guide to what a flood risk assessment is and when planning requires one. For sites where an FRA is needed, three points matter most in 2026:
- Show the drainage hierarchy. Demonstrate you have tested infiltration first, then discharge to a watercourse, before defaulting to the sewer. Percolation testing early can save a redesign later.
- Restrict runoff and prove it. New development is generally expected to limit surface water runoff towards greenfield rates, with attenuation sized for design storms plus a climate change uplift.
- Account for surface water risk. The Environment Agency’s updated surface water mapping now feeds directly into planning — see our note on the 2026 Flood Map for Planning update. Screen your site against it and address any surface water flow paths in the strategy.
Does Schedule 3 not being commenced let you off?
No — if anything the opposite. Without a separate SuDS approval body, the entire burden falls on the planning application. Getting the drainage strategy right first time, to the National Standards, is what keeps an application moving and avoids a holding objection from the LLFA. A well-evidenced SuDS strategy is now one of the strongest things you can put in front of a planning officer.
How Fortress Associates can help
Fortress Associates produces automated, site-specific flood risk assessments for planning applications in England, using live Environment Agency data and following the EA’s FRA template. Every report includes a SuDS-based drainage strategy aligned with CIRIA C753 and the national standards for sustainable drainage. The report is free and ready in minutes — a fast way to see your flood zones, surface water risk and drainage requirements in one place. Try our flood risk assessment service, browse the full services page, or contact us with your site address.
Sources & further reading
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