Flooding, levels and surface water

Is SuDS Schedule 3 mandatory in England?

• England: not commenced. Schedule 3 remains on the statute book but has never been brought into force.
• Wales: in force since January 2019. The SuDS Approving Body regime operates there and has done for years.
• A 2023 government review concluded better delivery may come through planning policy rather than commencement.
• Check the jurisdiction before the deadline. Most of the confusion online comes from applying the Welsh position to English sites.

Why so much published guidance says the opposite

This is one of the most consistently misreported points in UK drainage, and it is worth being precise about, because a lot of material circulating online states that mandatory SuDS applies in England from a given year.

The confusion has two roots. The first is that Schedule 3 genuinely exists and genuinely is in force, just in Wales, where the SuDS Approving Body regime has operated since January 2019. Guidance written about Wales gets read as though it were national.

The second is that commencement in England has been announced as an intention more than once and then not carried through. In January 2023 the government published its review and signalled implementation, which generated a wave of content assuming a date had been set. The review itself concluded that better SuDS delivery may be achieved through improving planning policy, as well as adoption and maintenance, rather than through bringing Schedule 3 into force in England, with a final decision to follow in due course.

What actually applies to an English site today

Sustainable drainage in England is delivered through the planning system rather than through a separate approval body. For major development, broadly ten or more dwellings, the expectation is that SuDS are provided, applied by the Local Planning Authority in consultation with the Lead Local Flood Authority as statutory consultee.

The practical difference matters. Under a commenced Schedule 3 regime, drainage approval is a separate consent with its own approving body and national standards, and construction cannot begin without it. Under the planning route, drainage is a condition attached to planning permission, negotiated case by case, with the maintenance and adoption arrangements agreed as part of that.

For an operator inheriting a site, that means the drainage obligations sit in the planning conditions and any associated agreement, not in a SAB approval. That is the document to read.

What this means if you operate SuDS assets

Whichever route created them, attenuation basins, ponds, tanks and permeable systems are assets with a performance requirement, and the obligation to maintain them usually outlives everyone involved in approving them.

The recurring operational problem is that these assets are designed for a storm that happens rarely, then left unmonitored for years. Silt accumulates and reduces storage volume. Outlet controls block. Infiltration surfaces clog. None of this is visible on a dry day, and all of it reduces the volume actually available when the design storm finally arrives.

Level monitoring on an attenuation asset answers the question that inspection cannot: how much storage is genuinely available right now, and how does the asset behave through a real storm rather than a modelled one. A basin that fills faster than it should, or empties more slowly than its outlet design implies, is telling you something a visual check will not.