RIDA prepares SuDS Reports for planning applications, drainage conditions and development proposals across the UK.
A SuDS Report sets out how Sustainable Drainage Systems (SuDS) will manage surface water on a development site. The report can include runoff calculations, proposed discharge rates, attenuation requirements, infiltration feasibility, hydraulic modelling, SuDS components, exceedance routes and maintenance information.
Our engineers prepare the drainage calculations, drawings and technical information needed to present a clear surface water drainage proposal to the planning authority and, where relevant, the Lead Local Flood Authority.
We work with developers, architects, planning consultants, landowners and project teams on residential, commercial, industrial and mixed-use development.
For a quotation, send us the site location, proposed development layout, current planning status, any planning or LLFA drainage comments already received, and any surveys, drainage information or flood risk reports already available.
We can review the information, confirm the required SuDS Report scope and provide a fixed quotation.
We are experienced chartered engineers passionate about the quality of our flood and drainage advice with your design in mind.
The level of detail changes with the site, development scale, planning stage and local drainage requirements. Some applications need a concise drainage submission. Others need runoff calculations, storage calculations, hydraulic modelling, drawings, exceedance information and long-term maintenance proposals.
RIDA prepares the report around the planning requirement for the site. A report can support a new planning application, validation request, revised submission or drainage planning condition.
If the project needs the wider foul and surface water approach established rather than a report focused on sustainable surface water management, see our drainage strategy for planning service.
When Is a SuDS Report Required?
A SuDS Report may be needed where a development changes surface water runoff, increases impermeable area, changes drainage routes or creates a new surface water system.
Typical projects include residential schemes, commercial development, industrial development, mixed-use development, redevelopment sites and major development.
A report may be requested through local validation requirements, planning officer comments, Lead Local Flood Authority comments or a drainage planning condition.
The required scope is checked against the planning requirement, local drainage policy and any consultee comments issued for the application.
The report needs to explain the proposed surface water drainage system and provide the technical evidence required for the project stage.
The exact contents vary by site. A RIDA SuDS Report can include the sections below.
We review the existing site before defining the proposed drainage approach.
The review can cover existing site use, impermeable areas, topographical information, drainage records, nearby sewers and watercourses, ground conditions, flood risk information, runoff routes, planning constraints and proposed development levels where available. Current surface water planning data can form part of the review where surface water risk affects the proposal.
This establishes the starting point for the calculations and proposed surface water system.
The report can assess runoff from the site before and after development.
Calculations can cover greenfield runoff rates where relevant, existing runoff rates, proposed impermeable area, peak discharge rates, runoff volumes and restricted discharge rates.
These calculations provide the basis for flow controls and attenuation storage where runoff must be released at a controlled rate.
The report identifies how surface water is proposed to leave or be managed within the site.
The assessment can review rainwater reuse, infiltration to ground, discharge to a watercourse, connection to a surface water sewer or another suitable drainage system.
The proposed route is supported by the site information available at the planning stage.
Where runoff cannot leave the site at the rate it is generated, storage is required.
The report can calculate the attenuation volume and review suitable storage options such as detention basins, ponds, permeable paving, geocellular storage, tanks, oversized pipes and integrated surface water storage.
The storage calculation is coordinated with the proposed discharge rate, development layout, drainage levels and available space.
Hydraulic modelling can be included where the drainage system needs a more detailed performance check.
The model can test pipe capacity, flow controls, storage, surcharge, flooding, system outfalls, critical storm durations, design rainfall events and current climate-change allowances. Design rainfall events can be expressed using Annual Exceedance Probability with the relevant return period.
The modelling results support storage volumes, network sizes and flow control selections.
The report can identify suitable SuDS components and explain their function within the proposed surface water system.
These can include permeable paving, swales, rain gardens, filter strips, detention basins, ponds, green roofs, infiltration features, attenuation systems and flow control structures.
Selection is based on the site layout, ground conditions, available space, runoff characteristics and planning requirements.
The aim is to establish a drainage system that works for the development and meets the required drainage objectives.
The report can identify how surface water is expected to move across the site during rainfall above the main system design capacity.
Exceedance routes are reviewed against buildings, access routes, neighbouring land and proposed site levels.
Maintenance information can cover inspection, routine maintenance, sediment removal, vegetation management, access, flow controls, storage features and long-term responsibility for the system.
The terms SuDS Report, Sustainable Drainage Report and Sustainable Drainage Systems Report are used by different planning authorities and project teams.
The purpose is usually the same: to present the proposed surface water drainage approach and the technical evidence that supports it.
RIDA defines the report scope from the planning requirement rather than the document title. A Sustainable Drainage Report can include drainage principles, runoff calculations, storage calculations, SuDS components, modelling results, layouts, exceedance information and maintenance arrangements.
The information requested changes between authorities and applications.
A drainage submission can need to set out the proposed discharge route, existing and proposed runoff rates, discharge restrictions, attenuation volume, SuDS components, hydraulic performance, climate-change allowances, exceedance arrangements, water quality, maintenance and long-term management.
For major development, LLFA comments can form a key part of the planning review. Projects with wider drainage issues, revised layouts or detailed consultee comments can be reviewed through our drainage consultancy service.
For development in England, Policy F8 of the August 2026 National Planning Policy Framework covers Sustainable Drainage Systems and watercourses.
The policy links SuDS proposals to the National Standards for Sustainable Drainage Systems, maintenance arrangements and Lead Local Flood Authority advice for major development.
The National Standards cover runoff destinations, everyday rainfall, extreme rainfall and flooding, water quality, amenity, biodiversity, construction, operation and maintenance.
RIDA can prepare the calculations, drawings, modelling and drainage information needed to support the surface water element of a planning submission. Our August 2026 NPPF drainage changes article covers the current planning-policy changes affecting flood risk and drainage submissions.
Useful project information includes the site address or boundary, proposed development layout, topographical survey, drainage records, proposed levels, planning reference, planning authority comments, LLFA comments, flood risk information, ground investigation information, infiltration test results where available, sewer information and proposed development areas.
You do not need every item before contacting us.
Send the information already available. We can confirm any information gaps before the report starts.
The core starting information is the site location, proposed layout and planning status.
A topographical survey, drainage records, flood risk information, ground information and consultee comments can reduce uncertainty in the drainage scope.
Where infiltration data is already available, it can be used in the drainage assessment and design calculations.
We review the development layout, planning status, drainage information, flood risk information and comments already issued by the planning authority or LLFA.
This establishes the report scope and identifies missing information.
We assess the proposed discharge route and the site constraints affecting surface water management.
This stage sets the drainage principles used in the calculations and report.
We calculate the relevant runoff rates, proposed discharge rates and attenuation requirements.
Hydraulic modelling is completed where required by the proposed system or planning submission.
We identify suitable SuDS components and coordinate them with the site layout.
The proposed approach can address runoff control, storage, water quality, exceedance and maintenance.
We compile the agreed planning submission package.
The package can contain the SuDS Report, runoff calculations, attenuation calculations, hydraulic model results, drainage layout, flow control information, exceedance information, maintenance schedule and technical appendices.
A planning authority or LLFA may request clarification or revisions after reviewing the submission.
Where response work forms part of our instruction, we can review the drainage comments, update the relevant calculations or drawings and prepare the technical response.
The terms can overlap in planning practice, but RIDA uses them for different service intents.
A SuDS Report focuses on sustainable surface water management and the evidence that supports the proposed drainage approach.
A Drainage Strategy sets out the wider drainage principles for the development and can cover foul and surface water drainage.
A SuDS Report can contain runoff calculations, attenuation calculations, SuDS proposals and hydraulic evidence. A Drainage Strategy can establish foul and surface water discharge routes, wider drainage principles and the basis for later design. Where the project needs the foul drainage system developed separately, see our foul water drainage design service.
A SuDS Report is the planning and technical document used to explain the proposed sustainable surface water drainage approach.
It records the drainage basis, calculations, proposed components and technical evidence required for the project stage.
SuDS Design develops the engineering detail of the proposed system.
This can include hydraulic modelling, drainage layouts, attenuation structures, levels, flow controls, detailed sizing and coordination with the wider development.
A project can start with a SuDS Report for planning and move into detailed SuDS Design after the drainage principles are accepted. Where the project progresses into construction-level pipework, levels, manholes, drainage networks and drawings, see our detailed drainage design service.
We prepare SuDS Reports for housing developments, apartment schemes, replacement dwellings and other residential projects.
The report can cover runoff, attenuation, infiltration, discharge restrictions, proposed SuDS components and planning requirements.
Commercial and industrial sites can generate significant runoff from roofs, parking and hardstanding.
The report can assess runoff control, surface water storage, water quality and the proposed discharge system.
Mixed-use sites can contain several drainage catchments and different types of impermeable area.
The SuDS Report can coordinate the surface water approach across the site and set out how the drainage catchments interact.
Smaller developments may still need surface water drainage information where impermeable area increases or the planning authority identifies a drainage issue.
The report scope can be proportionate to the development and the planning request.
Major development can need detailed drainage evidence, including LLFA consultation, runoff calculations, hydraulic modelling, storage assessment, exceedance routes, maintenance information and coordination with flood risk work.
The cost of a SuDS Report is based on the technical work needed for the site.
Key pricing factors include site size, development type, planning stage, available survey information, number of drainage catchments, discharge constraints, hydraulic modelling, attenuation calculations, drawings, planning comments and flood risk work required with the report.
For a fixed quotation, send us the site location, proposed layout and planning status.
If you have received a validation request, drainage objection or LLFA response, send it with the enquiry. This helps us price the work against the actual planning requirement.
A SuDS Report deals with surface water drainage.
A Flood Risk Assessment deals with flood risk to and from the development. Some projects need both documents.
A combined flood risk and drainage package may be appropriate where the site is affected by flood risk, lies within a flood zone, has surface water flood risk, receives a planning request for both documents, or needs drainage design coordinated with flood risk mitigation.
The Flood Map for Planning can provide an early indication of fluvial and tidal flood-zone constraints. Current NaFRA2 flood risk data can provide further context where wider flood risk needs to be reviewed with the drainage proposal.
Where both services are required, the drainage calculations and flood risk evidence can use the same development information and site assumptions. See our Flood Risk Assessment for Planning service.
Our work combines drainage engineering with planning submissions, flood risk assessment and development constraints.
This keeps the report focused on the technical questions raised by the site and planning process.
RIDA can develop the hydraulic model used to assess storage, network performance and proposed flow controls.
The report and modelling are prepared as one coordinated drainage package.
The report sets out the site information, calculations, drainage approach and supporting drawings in a clear technical format.
We review the project information before confirming the scope.
The quotation states the agreed work so the client knows what is included before the report starts.
Where drainage comments have already been issued, we can review them before starting the report.
The scope can then address the points raised by the planning authority or LLFA.
Use real RIDA projects in this section. Each case study should state the site, drainage issue, RIDA response and outcome.
Recommended title formats:
Until a dedicated SuDS case study is published, link the section to drainage and flood risk projects. Replace this with the strongest SuDS-specific case study once live.
For projects that need the wider foul and surface water drainage principles established for planning.
For engineering design of the proposed sustainable surface water drainage system.
For detailed foul and surface water networks, levels, pipework, manholes and construction information.
A SuDS Report explains how surface water runoff from a proposed development will be managed.
It can include the proposed discharge route, runoff calculations, attenuation requirements, SuDS components, hydraulic modelling, exceedance routes, drawings and maintenance information.
A planning authority may request a SuDS Report or equivalent drainage information where a development could affect surface water drainage.
The level of information changes with the site, development scale and local planning requirements.
A report can include site drainage review, runoff calculations, discharge rates, attenuation storage, infiltration assessment, SuDS proposals, hydraulic modelling, drainage drawings, exceedance routes and maintenance arrangements.
The final contents are based on the planning requirement and project stage.
The fee is based on site size, development type, available information, drainage constraints, modelling requirements and the drawings or calculations needed.
Send us the site layout and planning information for a fixed quotation.
The programme is based on the project scope and the information available at instruction.
A site with the required surveys, drainage records and development information can progress directly into calculations and reporting. Missing information may need to be resolved before parts of the report can be completed.
We confirm the programme with the quotation.
Yes, where the information requested by the planning condition falls within the agreed report scope.
The condition wording should be reviewed before work starts so the submission addresses each drainage requirement.
A SuDS Report focuses on sustainable surface water management.
A Drainage Strategy covers the wider drainage approach and can include foul and surface water drainage.
Planning authorities can use these terms differently, so we review the planning requirement before confirming the service scope.
A SuDS Report presents the drainage proposal and technical evidence.
SuDS Design develops the engineering detail of the system.
A planning-stage report may contain an outline design, with detailed drainage design completed later in the project.
A Flood Risk Assessment may be needed where the development is affected by flood risk or where planning policy and local requirements call for a site-specific assessment.
We can review the planning context and confirm whether separate flood risk work is needed with the SuDS Report.
Yes.
Send us the LLFA response, planning officer comments and the drainage information already submitted.
We can review the points raised and confirm the technical work needed for a response.
Send us your site location, proposed layout and current planning status.
If you already have a planning reference, LLFA response, drainage condition or validation request, include it with the enquiry.
We will review the project information, confirm the required SuDS Report scope and provide a fixed quotation.