A surface water drainage strategy is required in the following circumstances:

  • Development site area over 1ha
  • Properties with more than 10 dwellings
  • Floor space over 1000m2
  • Minor development of less than 10 dwellings located within an area at risk of flooding, or within an area identified as having critical drainage problems
  • Any development where there is an increase in impermeable areas and the Local Planning Authority is concerned about the cumulative impact of extensions

Surface Water Drainage Strategies are also frequently conditioned as part of planning permission, so even if your site isn’t in an area identified as at risk of flooding, you may still require a survey to determine whether a strategy needs to be put in place.

What is a surface water drainage strategy?

A surface water drainage strategy investigates surface runoff from a site and determines if and how it needs to be managed to comply with the requirements of the NPPF, the Environment Agency or local planning policies.

What is SuDS?

SuDS or Sustainable Drainage Systems are a natural approach to managing drainage and work by slowing and holding back the water that runs off the site.

Planning policy dictates that developments should utilise SuDs unless there are practical reasons for not doing so, and should aim to manage surface water runoff as close to its source as possible in line with the drainage hierarchy:

  • Store rainwater for later use
  • Use infiltration techniques, such as porous surfaces in non-clay areas
  • Attenuate rainwater in ponds or open water features for gradual release
  • Attenuate rainwater by storing in tanks or sealed water features for gradual release
  • Discharge rainwater direct to a watercourse
  • Discharge rainwater to a surface water sewer/drain
  • Discharge rainwater to the combined sewer

What do drainage strategy reports contain?

  • Describe the existing and proposed drainage arrangements
  • Calculate the existing and proposed surface water runoff using industry standard MicroDrainage software.
  • Assess the suitability of SuDS options and propose appropriate elements to meet the runoff rate requirements based on national and local planning policy.
  • Provide an indicative drainage layout
  • Complete the report as a standalone document or incorporate it within a Flood Risk Assessment report

Drainage strategy or detailed drainage design?

A surface water drainage strategy is normally sufficient for a planning application, however, a detailed drainage design can be required or made a condition of planning for some sites.

Our detailed drainage design report is available as a package with our SuDs report and Flood Risk Assessment or as a single service.

Benefits of a surface water drainage strategy report from Your Environment

  • Professional advice about surface water drainage and SuDS
  • All Surface Water Drainage Strategy recommendations are provided in accordance with the latest industry standards
  • Our engineers are extensively qualified and use the latest equipment
  • We provide a cost-effective drainage strategy to meet the required national and local policies. Many of our drainage services can also be provided as packages to help keep costs down as well as your site development running smoothly
  • Easy to understand, jargon-free reports


Need a Surface Water Drainage Strategy? Contact us here to talk to a member of our team or request a free, no-obligation quote.