SuDS approval: in force in Wales since 2019, still not in England
TL;DR. SuDS approval under Schedule 3 has been in force in Wales since 2019 and has still not been commenced in England. Where it applies, no construction work with drainage implications may begin until a drainage system has been approved, and the right to connect surface water to a public sewer becomes conditional on that approval. Either way, the harder problem is the one Defra’s own review named: making sure the drainage still works once the developer has left.
Key takeaways
- Schedule 3 of the Flood and Water Management Act 2010 came into force in Wales on 2 May 2018 for specified purposes, with full implementation on 7 January 2019.
- Paragraph 7 states that construction work which has drainage implications may not be commenced unless a drainage system for the work has been approved by the approving body.
- Schedule 3 makes the right to connect surface water runoff to public sewers conditional on that approval.
- Defra’s implementation review does not support the option of continuing to deliver SuDS purely through the planning process.
- The review names difficulties of ensuring proper maintenance once the developer has left the site.
- An attenuation asset that silts up, blocks or stops draining fails silently, because nothing about it is instrumented by default.
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Last updated: 27 August 2026
What is SuDS approval under Schedule 3?
SuDS approval under Schedule 3 is a consenting regime for drainage, separate from planning permission. It runs through an approving body, commonly called a SuDS Approving Body or SAB, sets national standards for the design, construction, operation and maintenance of sustainable drainage, and puts a gate in front of construction.
The gate is the sharp part. Paragraph 7 of the Schedule states that construction work which has drainage implications may not be commenced unless a drainage system for the work has been approved by the approving body. Construction work is defined broadly, covering anything done by way of, in connection with or in preparation for the creation of a building or other structure that affects the land’s ability to absorb rainwater.
The second lever of SuDS approval is the connection. Schedule 3 amends the Water Industry Act 1991 so that surface water may only be connected to a public sewer where the drainage system has Schedule 3 approval and that approval included a proposal for communication with the sewer. Defra’s review puts it plainly: it makes the right to connect surface water runoff to public sewers conditional on the drainage system being approved before any construction work can start.
Third, SuDS approval carries adoption. The approving body must adopt a drainage system where it was constructed in line with the approved proposals and qualifies as a sustainable drainage system. Adoption does not extend to single-property systems, publicly maintained roads, or systems built under specific water industry provisions.
Where does SuDS approval apply today?
In Wales. Schedule 3 came into force in Wales on 2 May 2018 for specified purposes, with full implementation on 7 January 2019. Welsh developments have therefore been going through SuDS approval for years, with the national standards and the adoption route operating as designed.
In England SuDS approval has not been commenced, so drainage for new development continues to be handled through the planning system and building regulations. That is the status quo Defra’s own review examined, and the review’s conclusion was blunt: it does not support the option of continuing to deliver SuDS purely through the planning process, nor does it support an alternative approving body to the unitary authorities or county councils.
For anyone planning an estate, a campus or a housing scheme, the practical reading is that the direction of travel is settled even where the commencement date is not. Standards for design, construction and maintenance are tightening either way, and the asset you build now is the asset that will be judged against them.
Why is maintenance the part that actually fails?
Because SuDS approval is a one-off event and drainage performance is a thirty-year problem. Defra’s review is explicit about the gap, recording concerns about unsatisfactory standards of design and construction, and about the difficulties of ensuring proper maintenance once the developer has left the site. SuDS approval proves the design was right on paper. Nothing in that process proves the basin still drains in year twelve.
SuDS assets degrade in ways that are invisible from the surface. An attenuation basin silts up and loses storage volume. A permeable surface clogs and stops infiltrating. A flow control device blocks with debris and either throttles too hard or passes too much. A tank fills with sediment. None of these announce themselves. The system simply performs worse than the approved design, and nobody knows until a storm arrives that the original calculation said it should have handled.
That is the honest weakness of any SuDS approval regime, in Wales or in England. It sets a standard at handover. The question of whether the asset still meets that standard a decade later is a monitoring question, and neither Schedule 3 nor planning policy answers it with data.
How do you monitor a SuDS asset?
By measuring level, because level is where performance shows itself. A basin or tank that is holding more than it should, draining slower than it should, or failing to empty between events is telling you its usable volume and its discharge rate have changed. Both are the numbers the SuDS approval was granted on.
- Baseline the empty level and the normal drain-down time in the first year, while the asset is known good.
- Track drain-down after each storm. A lengthening curve is siltation or a partly blocked control, long before either is visible.
- Alarm on a level that does not return to baseline, which means the asset is entering the next storm already part full.
- Record it, so the adopting body or the estates team has evidence rather than an opinion at the next inspection.
AQUAIOT Radar suits this because it never touches the water. It is 60 GHz non-contact level sensing accurate to within ±2 mm, reading through foam, vapour and condensation, with ATEX variants where a chamber requires them. In an attenuation tank, a basin, a swale outfall or a below-ground crate system, there is nothing submerged to foul, silt up or need cleaning, which matters on an asset whose whole failure mode is sediment.
Upstream of the basin, the AQUAIOT Smart Water Butt is the rainwater harvesting end of the same logic, using rainfall-aware control to free up storage capacity before a storm rather than sitting full when one arrives. Everything reports over encrypted cellular and LoRaWAN into the AQUAIOT Cloud, with threshold alarms, trendlines and exports, plus open APIs where a council or an asset manager needs the data in their own system.
Frequently asked questions
Is SuDS approval mandatory in England?
Not currently. SuDS approval under Schedule 3 has not been commenced in England, so drainage for new development is handled through planning and building regulations rather than through a SuDS Approving Body. It is in force in Wales, where it came into effect for specified purposes on 2 May 2018 and fully on 7 January 2019.
What is a SuDS Approving Body?
It is the body that grants SuDS approval under Schedule 3 and, where the conditions are met, adopts the system for future maintenance. Defra’s implementation review supported the unitary authorities and county councils in that role rather than creating an alternative body. SuDS approval is separate from planning permission and covers design, construction, operation and maintenance against national standards.
Does SuDS approval stop you connecting to a public sewer?
It makes the connection conditional rather than automatic. Where SuDS approval applies, surface water may only be connected to a public sewer if the drainage system has been approved and the approval included a proposal for communication with the sewer. That removes what was effectively an automatic right to connect, which is the mechanism that gives the regime its teeth.
Who maintains a SuDS asset after handover?
It depends on whether the asset is adopted. Under the SuDS approval regime the approving body must adopt systems built in line with the approved proposals, with exclusions for single-property systems, publicly maintained roads and certain water industry systems. Where an asset is not adopted, responsibility stays with the landowner or a management company, which is where Defra’s concern about maintenance after the developer leaves bites hardest.
What to do while the legislation settles
Waiting for a commencement date is not a drainage strategy. The assets are already in the ground, the standards are already tightening, and the failure mode is already running: sediment accumulating quietly in basins and tanks that were signed off years ago and have not been measured since.
Instrumenting them is cheap next to rebuilding them, and it turns an inspection opinion into a drain-down curve. Speak to an AQUAIOT engineer about levelling the attenuation assets on your site and baselining them while they still perform.
By GP, Digital and IoT lead at AQUAIOT.