Wales: SuDS approval bodies and Schedule 3 consent
Wales brought Schedule 3 of the Flood and Water Management Act 2010 into force, creating a separate drainage approval. Here is what needs it, what to submit and how adoption works.
This article covers Wales only. In Wales, a SuDS approval body consent is a separate statutory approval from planning permission, and construction cannot lawfully begin without it. Schedule 3 to the Flood and Water Management Act 2010 was brought into force in Wales in January 2019, so new development with drainage implications on a construction area of 100 m² or more, or serving more than one property, needs approval from the SuDS approving body, which is the unitary local authority. England has not brought Schedule 3 into force and still controls surface water drainage through planning conditions instead.
Treating the two consents as one process is the mistake that stalls Welsh schemes at the point the contractor arrives on site.
Why Schedule 3 is in force in Wales and not in England
Schedule 3 creates a standalone approval regime for surface water drainage, with national standards, a statutory approval body, an adoption duty and enforcement powers. Welsh ministers switched it on, with a set of statutory standards published to sit beneath it. In England the equivalent provisions are still not in force, and surface water is handled through the planning system, with the lead local flood authority acting as a statutory consultee on major development.
The practical difference for an applicant is sequencing and risk. In England, a drainage strategy is submitted with the planning application and the detail is usually secured by condition. In Wales, there is a second application, to a different team, with its own validation requirements, its own fee and its own determination period, and the approval has to be in place before construction starts rather than before occupation.
Which construction needs approval
The trigger is construction work with drainage implications. Two thresholds bring a scheme in.
| Trigger | Position |
|---|---|
| Construction area of 100 m² or more | Approval required |
| Drainage serving more than one property | Approval required, whatever the area |
| Single property, construction area under 100 m² | Outside the regime |
| Exemptions in the legislation | A small number apply, for example certain highway and sewer works |
Construction area is not the same as building footprint. It takes in the area of the construction works with drainage implications, so hardstanding, driveways and areas of ground disturbance all count, and a modest house on a large plot with a long drive can cross the threshold comfortably.
And a single dwelling can therefore need approval. That catches self-builders who have assumed the regime applies only to estates.
The national standards applied
The statutory standards published by the Welsh Government set out what an acceptable system looks like, and they cover six areas: the destination of surface water runoff, hydraulic control of flows and volumes, water quality, amenity, biodiversity and the construction, operation, maintenance and structural integrity of the system.
The runoff destination standard drives the design. It works as a hierarchy: surface water should be collected for reuse, then discharged to ground through infiltration, then to a surface water body, then to a surface water sewer, with discharge to a combined sewer the last resort. Each step down the hierarchy has to be justified with evidence, which in practice means infiltration testing results rather than an assertion that the ground is clay.
Hydraulic control deals with rates and volumes, including the greenfield runoff rate for the site, long term storage where volumes exceed greenfield, and an allowance for climate change. Water quality is addressed through the treatment train, with the number and type of treatment stages matched to the pollution hazard of the surface being drained. Amenity and biodiversity standards push towards above ground, vegetated features rather than buried tanks, which is the point most engineers find hardest.
Application content and fees
A SuDS approving body application is a technical submission, not a narrative one.
- A drainage layout showing the full system, catchment areas and the outfall.
- Infiltration testing results, with the method and locations, or evidence why infiltration is not viable.
- Hydraulic calculations for the design events and the exceedance route for events beyond design.
- Greenfield runoff rate calculations and the proposed discharge rate.
- Treatment train design against the pollution hazard indices for each surface.
- Construction details and specifications for each component.
- A maintenance schedule with responsibilities, frequencies and access arrangements.
- Evidence of the discharge agreement where the outfall is to a sewer or watercourse.
Fees are set by regulations and scale with the construction area, so confirm the current schedule with the approving body before budgeting. Determination periods are also set in the Regulations, with a standard period of several weeks and a longer period where environmental impact assessment is involved, and the clock only starts on a valid application. Invalid submissions are common, usually for missing infiltration testing or an absent maintenance schedule.
Illustrative example: a plot for two dwellings on the edge of a Welsh town, with clay subsoil and no watercourse within reach. Infiltration testing confirms soakaways are not viable. The design uses permeable paving over an attenuated sub-base, a swale along the plot boundary and a flow control at the outfall to the public surface water sewer, with the discharge rate limited to the calculated greenfield rate. Because the system serves two properties, adoption applies and the construction details have to satisfy the approving body's adoption requirements.
Timescales and the relationship with planning
The two applications can run in parallel, and on most schemes they should. Submitting the drainage design to the approving body at the same time as the planning application surfaces conflicts early, because a SuDS layout that needs a 12m wide swale along the frontage changes the site layout that the planning application is relying on.
What you must not do is secure planning permission, mobilise a contractor and then discover that the approval has not been granted. Construction without approval is an offence, and the approving body has powers to require works to be altered or removed.
In England the equivalent material sits in the planning submission, and our Drainage Strategy page explains what that document covers. A Welsh scheme still needs a drainage strategy for the planning application, addressing Planning Policy Wales and the relevant technical advice note, alongside the separate approval application. Where the site is in a flood risk area, the flood consequences assessment required by Welsh policy is a further document again, and the Flood Risk Assessment page covers the English equivalent for comparison.
Adoption and maintenance
Where a system serves more than one property and is built in accordance with the approval, the approving body has a duty to adopt it. That is a substantial difference from England, where management companies and residents' arrangements carry long term maintenance on most new estates.
Adoption is not automatic on completion. It follows inspection and confirmation that the system was constructed as approved, which makes construction supervision and as-built records important. Keep photographs of buried components before they are covered, since proving a sub-base build-up after the fact is close to impossible.
For single property systems, maintenance stays with the owner, and the maintenance schedule submitted with the application is the document a future buyer's solicitor will ask for. Foul drainage is a separate matter again, handled through the water undertaker and, where relevant, the Foul Sewage Assessment for the planning submission.
Enforcement if work starts without approval
Carrying out construction work requiring approval without that approval is an offence, and the approving body can serve notice requiring alteration or removal of the drainage system. Retrospective approval is possible in some circumstances but should not be the plan.
The commercial consequence is usually worse than the legal one. A system built without approval may not be adopted, which leaves the long term maintenance liability with the developer or the residents, and it will be found at the point of sale. Mortgage lenders and buyers' solicitors ask about SuDS approval and adoption status on new Welsh housing.
You can see which supporting documents a scheme is likely to need by entering the postcode on PlanScope, bearing in mind that PlanScope's drafting is grounded in English national policy and local plans, so a Welsh application needs the reviewer to check Planning Policy Wales and the relevant technical advice notes.
This is general guidance, not legal advice. Thresholds, fees and determination periods are set by Welsh regulations and are amended from time to time, so confirm the current position with your SuDS approving body before relying on it.
PlanScope provides AI-assisted draft reports for planning applications. Reports should be reviewed before submission. We do not guarantee planning approval.
Frequently asked questions
What is a SuDS approving body in Wales?
The unitary local authority acting under Schedule 3 to the Flood and Water Management Act 2010, which Wales brought into force in January 2019. It approves surface water drainage designs against the Welsh statutory standards, adopts qualifying systems and enforces the regime. It is a separate function from the planning service, with its own application and fee.
What size of development needs SuDS approval?
Construction work with drainage implications on a construction area of 100 m² or more, or any drainage serving more than one property whatever the area. Construction area includes hardstanding and ground disturbance, as well as the building footprint, so a single house with a long driveway can cross the threshold.
Does England have the same regime?
No. Schedule 3 is still not in force in England, where surface water drainage is controlled through the planning system with the lead local flood authority as a statutory consultee on major development. That is why an English drainage strategy is usually secured by condition rather than by a separate approval.
Can I start construction before approval is granted?
No. Carrying out construction work that requires approval without it is an offence, and the approving body can require the drainage system to be altered or removed. The approval must be in place before construction begins, which is earlier in the programme than most English practitioners expect.
Who maintains an approved SuDS scheme?
Where a system serves more than one property and is built in accordance with the approval, the approving body has a duty to adopt it, following inspection and confirmation of as-built compliance. Systems serving a single property stay with the owner, under the maintenance schedule submitted with the application.
What makes applications invalid most often?
Missing infiltration testing results and an absent maintenance schedule. The runoff destination standard works as a hierarchy starting with reuse and infiltration, so stepping down to a sewer discharge has to be justified with test data rather than an assertion about the ground conditions.
Sources and further reading
This article is general guidance about the planning system in England and, where stated, the rest of the UK. It is not legal or professional advice. Check your local planning authority’s validation requirements and take professional advice for your specific site.