Schedule 3 SuDS approval: where the law stands and what to do now

Schedule 3 to the Flood and Water Management Act 2010 is on the statute book and, in England, still not in force. As at September 2026 there is no SuDS Approving Body in England, no separate SuDS approval to obtain, and the automatic right to connect surface water to a public sewer has not been removed. In Wales, the same Schedule has been in force since January 2019, and a separate approval from the SuDS Approving Body is required before construction begins on qualifying work.

That gap between the two nations is the practical point. English drainage design is controlled through the planning system and Building Regulations. Welsh drainage design has an extra consent with its own application, fee, standards and construction inspections.

Government has said at various points that it intends to implement Schedule 3 in England, and has also considered delivering the same outcomes through improvements to the planning system instead. Verify the current position on gov.uk before advising a client, because this is exactly the sort of commitment that moves.

What controls surface water drainage in England now

Four mechanisms do the work, and a drainage strategy has to satisfy all of them.

National policy requires sustainable drainage systems on major development, and expects them on other development where there is a flood risk. That is the hook the local planning authority uses.

The lead local flood authority is a statutory consultee on surface water drainage for major development, under the development management procedure order. Its comments are the ones that decide most applications, and they are made against local standards that vary by county.

The Defra non-statutory technical standards for sustainable drainage systems set out the peak flow control, volume control, structural integrity and maintenance expectations. They are non-statutory, and they are still the reference point most authorities cite.

Building Regulations Part H sets the drainage hierarchy: infiltration first, then discharge to a watercourse, then to a surface water sewer, then to a combined sewer. Departing from that order requires evidence, not assertion.

What a drainage strategy has to demonstrate

The content is stable across most English authorities, whatever the local standard says about rates.

1. Existing site characteristics: topography, geology, infiltration testing results, groundwater levels, existing drainage and any watercourses.
2. The proposed discharge point and the justification for it against the hierarchy, with correspondence from the sewerage undertaker where a sewer connection is proposed.
3. Greenfield or existing run-off rates, with the method and the parameters shown, and the proposed discharge rate.
4. Storage volumes for the design events, including the 1 in 100 year event with an allowance for climate change taken from the current published allowances.
5. Water quality management, using the simple index approach or an equivalent method, showing that the pollution hazard from the proposed land use is matched by the mitigation indices of the treatment train.
6. Exceedance routes, showing where water goes when the system is overwhelmed, and confirming that it does not enter buildings or leave the site uncontrolled.
7. Maintenance: who owns each component, who maintains it, on what schedule and funded how, for the life of the development.

Infiltration testing is the item most often missing. Soakaway design without site-specific infiltration results, carried out at the depth and location of the proposed feature, is an assumption rather than a design, and lead local flood authorities say so.

A Drainage Strategy that covers those seven elements survives consultation. One that presents a storage volume and a discharge rate without the evidence behind them does not.

Where drainage meets the flood risk assessment

The two documents overlap and are frequently inconsistent, which consultees notice.

A Flood Risk Assessment deals with the risk of flooding to and from the development, across all sources. The drainage strategy deals with how surface water is managed on the site. Finished floor levels, climate change allowances and the assumed discharge point have to be identical in both.

Foul drainage is separate again. Capacity at the receiving treatment works and in the network is the undertaker's judgement, and on a constrained network it is a programme risk that no amount of design changes. A Foul Sewage Assessment establishes the position early, and a Utilities Assessment covers the wider connections that tend to surface late.

Adoption, and the question nobody asks early enough

Every drainage component needs a long term owner. Get this wrong and the scheme reaches the section 106 stage with an unresolved liability.

Sewers and some SuDS components can be adopted by the sewerage undertaker under a section 104 agreement, subject to the current design and construction guidance. Highway drainage can be adopted by the highway authority under a section 38 agreement. Open features such as basins, swales and ponds are often left to a management company funded by an estate charge, or occasionally to the local authority with a commuted sum.

Ask three questions at concept design. Which components are the undertaker willing to adopt under the current guidance? Which will the highway authority take? And who maintains the rest, funded by what, for how long?

The answers shape the design. A component nobody will adopt tends to be redesigned into one somebody will.

If Schedule 3 is brought into force in England

The Welsh experience shows what changes, and it is more than an extra form.

In Wales, approval is needed for construction work with drainage implications where the area affected reaches the threshold set in the legislation, which catches schemes far smaller than the English major development trigger. Welsh applicants should check the national standards published by the Welsh Government, since planning policy there sits in Planning Policy Wales and the accompanying technical advice notes rather than in the NPPF.

What to do now, whichever way it goes

Design as though the standards already applied. The technical content of a compliant Welsh submission and a good English drainage strategy is largely the same, and a scheme designed to the national standards will not need reworking if the position changes.

Then protect the programme. Build infiltration testing into the site investigation rather than commissioning it separately after a consultee objection. Get the undertaker's position on the discharge point in writing before the layout is fixed. And settle adoption in principle before the legal agreement is drafted.

Illustrative example. A 90 unit scheme designs a swale and basin train discharging to a watercourse at greenfield run-off rate. Infiltration tests carried out late show a shallow water table, which rules out the infiltration elements in the treatment train and reduces the water quality indices below what the land use requires. Retrofitting a proprietary treatment device costs more than the earlier testing would have. This example is illustrative only.

One honest uncertainty. The position on bringing Schedule 3 into force has changed direction more than once, and anyone who tells you confidently what will happen next is guessing. Design to the standards, and check the current position at the point you advise.

This is general guidance, not legal advice. Check the position with your local planning authority, the lead local flood authority and the sewerage undertaker before relying on it.

Browse the PlanScope report types to see which flood and drainage documents your scheme is likely to need.

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