London flood & drainage planning intelligence: SuDS conditions, discharge refusals and the borough league

What read planning decision notices reveal about drainage/SuDS conditions across London — and where developers are failing at the discharge stage.

Trails Research·Updated 2026-07-22·5 min read
From — read planning decision notices across London
—of —SuDS discharge-of-condition applications refused
—discharge refusal rate
—drainage-conditioned approvals (6 months)

Developers are failing at the discharge stage — the point where a drainage condition attached at approval must be signed off before work can start. Figures refresh as more decision notices are read.

When a London council approves a scheme, it increasingly attaches a sustainable-drainage (SuDS) or flood condition. Before work starts, the developer has to discharge that condition — submit the drainage details for sign-off. This page reads the resulting decision notices to show, in aggregate, how often that is happening and where it is going wrong. It is built from public planning records; individual schemes are not named.

Are SuDS discharge-of-condition applications being refused in London?

The live figure loads from the read decision notices. A refusal at the discharge stage does not mean the scheme was rejected — it means the drainage details submitted to satisfy the condition did not pass.

Which London boroughs are toughest for drainage conditions?

The borough league ranks councils by the share of approvals carrying a drainage/SuDS condition. Counts are always shown; each percentage appears only once its own sample is large enough to be reliable.

How has flood & drainage conditioning moved over the last 6 months?

The month-by-month trend builds as decision notices are read.

What do the drainage conditions actually demand?

Common condition themes — attenuation and storage, discharge-rate limits, maintenance regimes — surface here as the notices are read.

Where does this data come from?

Figures are built from read UK planning decision notices. Counts are always shown; each percentage appears only once its own sample is large enough to be reliable. Only aggregate figures are published here — never a scheme address, an application reference, or condition wording. For the full method, sources and refresh cadence, see the methodology page.

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Frequently asked questions

Are SuDS discharge-of-condition applications being refused in London?
Yes — a material share of drainage discharge-of-condition submissions (where a drainage condition attached at approval is submitted for sign-off before work starts) are being refused. The live figure on this page is computed from read planning decision notices across the covered London boroughs. Failing at the discharge stage is a distinct signal from refusal at the application stage: the scheme was approved, but the drainage details submitted to discharge the condition did not pass.
What share of London planning approvals carry a drainage or SuDS condition?
The page shows the current share by borough, computed from read decision notices. Rates vary widely and are withheld for boroughs below the coverage floor (too few read notices to be reliable) so a thin sample is never presented as a reliable rate. Sustainable drainage (SuDS) conditions are increasingly standard on approvals that add roof or hardstanding area, especially in surface-water flood-risk areas.
Which London borough is toughest for drainage conditions?
The borough league on this page ranks councils by the share of approvals carrying a drainage/SuDS condition (boroughs under the coverage floor are marked and their rates withheld). The ranking shifts as more notices are read, so treat it as directional. Toughness reflects both local flood-risk geography and each authority's drainage policy stance.
Where does this flood and drainage planning data come from?
It is derived from published UK planning decision notices read across the covered London boroughs — the same public records a planning officer issues on determination. Only aggregate rates are shown; individual scheme addresses and application references are not published here. See the methodology page for sources, the coverage floor, and refresh cadence.

About this data

This article uses live data from Trails Cost Tracker, aggregating ONS Construction Output Price Indices, DBT Monthly Building Materials Statistics. Data is auto-refreshed each quarter.

→ See the full Trails Cost Tracker→ Methodology and sources

About Trails

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