What does a SuDS planning condition actually require?

The recurring themes in drainage conditions on London approvals, and why the obligation does not end at design.

Trails Research·Updated 2026-07-29·5 min read
From our ongoing reading of London planning decision notices
… of drainage conditions fall in the most common theme
… only close after construction is finished

Conditions vary in wording but not much in substance. They cluster into a handful of recurring themes, and one of them lands after construction is finished.

A SuDS or drainage condition attached to a planning permission is a specific obligation, not a general instruction to drain the site properly. Reading the conditions recorded on London decision notices, they fall into a small number of repeating themes. Knowing which one you have got tells you what to submit.

What does a SuDS planning condition typically require?

The theme breakdown (attenuation and storage, discharge-rate limits, maintenance regimes, verification evidence) loads from the read notices and appears here once the sample is large enough to report.

Does the obligation end once the scheme is approved?

No. A meaningful share of conditions ask for evidence after construction (as-built drawings, verification reports, confirmation that the maintenance regime is in place).

Which changes who owns it. If a slice of your drainage conditions only close after practical completion, drainage is not a design-stage item that finishes when permission is granted; it is a handover deliverable somebody has to price, programme and actually produce. On a contract where the designer has long since demobilised, that responsibility has a habit of landing on nobody.

Are SuDS conditions mandatory on all developments?

Not universally, and there is a lot of wrong information about this online. Schedule 3 of the Flood and Water Management Act 2010, which would have made SuDS approval a statutory requirement with its own approval body, has not been commenced in England. It is in force in Wales.

In England the requirement comes through the planning system instead: strengthened NPPF policy and non-statutory national SuDS standards, applied by lead local flood authorities, with major development broadly meaning ten or more dwellings. Several sources state that Schedule 3 is now mandatory in England. It is not. If you are relying on a page that says so, check what else it has told you.

Where does this come from?

We read planning decision notices across inner- and outer-London boroughs as part of our monitoring work, and this page reports the patterns in what we have read. These are observations, not a census: our reading is deeper in some boroughs than others, and where it is still thin we hold a figure back rather than publish it. Proportions and rankings are published here; the underlying counts, and how much of each borough we have read, are on the London page. Only aggregate patterns appear here: never a scheme address, an application reference, or the wording of a condition. See the methodology page, the refusal grounds , or the full London flood & drainage picture .

Frequently asked questions

What does a SuDS planning condition typically require?
Conditions vary in wording but cluster into a handful of recurring themes. Source control and attenuation: limiting runoff, usually to greenfield rate, with storage sized and evidenced. A surface water drainage scheme or strategy setting out the design and the discharge hierarchy. Flood risk itself: finished floor levels, evacuation, and an assessment addressing the site’s actual risk sources. Maintenance and adoption arrangements covering who is responsible for the system over its life. And verification evidence: as-built drawings or a verification report confirming what was installed matches what was approved. This page ranks them by how often we see each one.
Does a SuDS obligation end once the scheme is approved?
No, and this is the shift worth planning for. A meaningful share of the conditions we read ask for evidence after construction: verification reports, as-built information, and confirmation that the maintenance regime is in place. That means the drainage obligation runs past practical completion, and someone has to own it. For a contractor or developer it is a handover deliverable to price and programme, not a design-stage item that closes when permission is granted. On a contract where the designer has long since demobilised, that responsibility has a habit of landing on nobody.
Are SuDS conditions mandatory on all developments?
Not universally. Schedule 3 of the Flood and Water Management Act 2010, which would have made SuDS approval a statutory requirement in England with its own approval body, has not been commenced. It is in force in Wales. In England the requirement comes through the planning system instead: strengthened NPPF policy and non-statutory national SuDS standards, applied by lead local flood authorities, with major development broadly meaning ten or more dwellings. Note that several sources online wrongly state that Schedule 3 is now mandatory in England; it is not.

About this data

This article reports patterns in UK planning decision notices that Trails reads across London local planning authorities, recomputed daily. Every figure carries its own sample, and the London page shows how much of each borough's decisions we have read.

→ The full London flood & drainage picture→ Methodology and sources

About Trails

Trails reads London planning decision notices every morning and shows flood and drainage consultants which schemes have just picked up a drainage condition, which discharge submissions were refused, and the architect behind each one.

See how Trails works for consultants →