Sustainable Drainage Systems (SuDS): guidance for developers

Last updated: 12 December 2022

What to provide as part of a full planning application

In addition to the information detailed within the outline planning applications section, you will be required to submit the following information for a full planning application:

  • a surface water drainage layout
  • calculations
  • maintenance plans
  • construction details
  • a water quality assessment
  • exceedance flow routes

The list is not exhaustive, the Lead Local Flood Authority may request additional information depending on site-specific conditions.

Read about full planning applications on the Planning Portal.

Surface water drainage layout

a. Outfall location, and if infiltrating site-specific infiltration rates

b. Easements (if required)

c. Buffer Distances (if required)

d. Pipe gradients/numbers/diameters

e. Manhole numbers

f. Slope/depths of basins/swales/ponds


Calculations must include structure and flow control details, total area, details of critical storm duration and must include a manhole schedule to be checked against the drainage layout


a. Details of what components will be maintained and how they will be maintained

b. Frequency at which tasks will be carried out

c. Responsibility for the maintenance (landowner/management company)

Construction details

In the form of site specific cross-sectional drawings and include:

a. Depths/diameters of pipes

b. Water levels

c. Lining if a lined component

Water quality assessment

You will need to carry out a water quality assessment using the simple index approach (or similar) as detailed in the CIRIA SuDS Manual (C753).

Exceedance flow routes

Provide details of proposed overland flood flow routes in the event of system exceedance or failure. You will need to demonstrate hat such flows can be appropriately managed on site without increasing flood risk to occupants, or to adjacent or downstream sites.