Enfield SuDS requirements: drainage strategy checklist
A practical list of the plans, calculations and forms Enfield asks for, with evidence from recent planning conditions.
The short version
Enfield asks for a sustainable drainage strategy with every planning application. Use the minor SuDS proforma for minor development and the full proforma for larger schemes. Sites in a flood-risk area also need a flood risk assessment.
- Planning trigger
- Drainage strategy with every application
- Local form
- Minor or full Enfield SuDS proforma
- Flood-risk sites
- Add a site-specific FRA
Use this as a starting point. Check the current validation list and the particular flood and drainage constraints on your site before submitting.
Start by confirming what the council asks for and which flood-risk tests apply to the site. Then use the document list and technical checks to set the scope. Further down, we look at the drainage conditions and refusal reasons found in the borough's decision notices.
When is a drainage strategy or FRA needed?
| Project situation | What to do | Status |
|---|---|---|
| Any planning application | Include a drainage strategy explaining where surface water will go and which SuDS measures are proposed. | Required |
| Minor development | Complete Enfield’s minor-development SuDS proforma and attach the plans and evidence relevant to the work. | Required |
| Larger or non-minor development | Use the full Enfield SuDS proforma with the drainage strategy and calculations. | Required |
| Site in a flood-risk area | Add a flood risk assessment addressing every relevant source of flooding. | Required |
| Infiltration proposed | Support the proposal with geology, groundwater and infiltration-test evidence. | Usually required |
What to send with the application
Prepare these first
- The correct Enfield SuDS proforma and a drainage strategy
- Existing and proposed plans, a topographical survey and the area draining to each part of the system
- Runoff and storage calculations that match the proposed layout
- The drainage hierarchy, exceedance routes and a maintenance plan
Add these if relevant
- Flood risk assessment where the site is in a flood-risk area
- Geology, groundwater and infiltration-test evidence where infiltration is proposed
- Connection evidence where discharge to a sewer or watercourse is proposed
What the drawings and calculations need to show
Map the site and what will drain
Show the existing site, the topographical survey, the proposed layout and the impermeable area draining to each part of the system.
Calculate runoff and storage
Show controlled discharge for the 1-in-1-year and 1-in-100-year events plus climate change, based on greenfield runoff rates, together with the required storage.
Evidence the drainage hierarchy
Explain the selected SuDS measures and support infiltration proposals with geology, groundwater and infiltration-test evidence.
Show exceedance and maintenance
Plot exceedance flow routes and provide a maintenance plan identifying the tasks, frequencies and responsible party.
Minor extension increasing the impermeable area
A householder extension adds roof area and alters the rear hardstanding, but the site is not shown in a fluvial flood zone.
- Use Enfield’s minor-development proforma. A small scheme is not exempt from the drainage requirement.
- Show the existing and proposed permeable areas and where the additional roof runoff will be managed.
- Support the preferred SuDS option and identify an alternative if testing or levels rule it out.
- Show exceedance routes on the layout and include a short maintenance schedule.
This example shows how the submission might be assembled. It is not a drainage design. The final scope depends on the site and the proposal.
Official forms and guidance
- Enfield Council: sustainable drainage systems
- GLA: London Sustainable Drainage Proforma
- GOV.UK: when a flood risk assessment is required
- GOV.UK: national standards for sustainable drainage systems
These links were checked 3 September 2026. Forms and validation requirements do change, so check the council website again before issuing the application.
Observed planning-condition data
What the drainage conditions actually ask for
The theme breakdown appears once enough drainage-conditioned approvals have been read to report it reliably.
Allow for discharge before agreeing a start date
There are not yet enough records to publish a reliable borough figure. Check the exact wording on the permission before agreeing the programme.
- Copy the condition into a schedule and list the evidence that answers each clause.
- Check that the calculations, drawings, specifications and maintenance plan use the same assumptions and references.
- For a pre-commencement condition, secure the written discharge before starting any work covered by the restriction.
- Where the condition asks for verification, keep site photographs, installation records and as-built information.
Understand the programme effect of a pre-commencement condition .
Reasons drainage submissions are refused
We have not read enough refusals in Enfield to publish a useful local breakdown. The London-wide analysis is available for wider context.
Projects attracting these conditions
There are not yet enough records to publish a reliable project-type breakdown.
About the data
The observed figures are computed from the planning decision notices from Enfield and are recalculated as we read more. We do not publish a rate when its sample is too small. This is not a complete record of every decision made by the authority, and it cannot tell you whether a document will be accepted for a particular site. Only aggregate figures appear here. See the full methodology or the London-wide picture.
Working in another borough? Compare drainage conditions and refusal patterns across London, then look at the individual schemes and project teams behind the figures.
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