The CIRIA SuDS Manual (C753): What It Is and How to Use It in 2026
Estimated reading time 11 minutes
The CIRIA SuDS Manual (C753) is the UK's principal design guide for sustainable drainage systems: 968 pages covering how SuDS should be planned, designed, built, operated and maintained. CIRIA published it in November 2015 to replace the original 2007 manual, and more than a decade later it is still the document a Lead Local Flood Authority means when it asks whether a drainage strategy "accords with the SuDS Manual". This guide covers what C753 contains, whether it is still current in 2026, how to download it free of charge, and how it now sits alongside the 2025 National Standards for SuDS.
No replacement for C753 has been announced as of July 2026. The 2015 manual, now on Version 6, remains the technical benchmark for SuDS design, and the full 968-page PDF is free to download.
What is the CIRIA SuDS Manual (C753)?
C753 is a best-practice guide to sustainable drainage published by CIRIA, the construction industry's research association. It pulls the planning, design, construction, operation and maintenance of SuDS into a single reference, built on the principle that surface water is a resource to be managed for benefit rather than a nuisance to be piped away. It is guidance, not statute, but in practice it defines what competent SuDS design looks like.
The Manual began as a Defra and Environment Agency research project (SC120084, under the joint Flood and Coastal Erosion Risk Management R&D programme) that started in 2013. What was commissioned as a revision of the 2007 manual turned into a complete rewrite. The authoring team was led by Bridget Woods Ballard of HR Wallingford, and the project's co-funders ranged from the Environment Agency and the Welsh Government to SEPA and the Northern Ireland Environment Agency, which is one reason the Manual is written for the whole of the UK rather than England alone.
- Published: November 2015 by CIRIA (reference C753, ISBN 978-0-86017-760-9).
- Replaces: C697, the original 2007 SuDS Manual.
- Written by: an HR Wallingford-led team under principal author Bridget Woods Ballard, steered by a large industry group.
- Commissioned as: Defra / Environment Agency FCERM research project SC120084.
- Current version: Version 6, incorporating minor amendments made in 2016, 2018 and 2019.
- Cost: free as a PDF (reference C753F); £250 for a printed copy.
What's inside the SuDS Manual?
C753 runs to 968 pages and 36 chapters, organised into five parts plus appendices. Part B sets the design philosophy, built around the four pillars of SuDS: water quantity, water quality, amenity and biodiversity. Parts C and D do the technical heavy lifting, and the appendices carry the checklists and the worked design example that practitioners use week to week.
Introduction
What the Manual is for and how to use it.
Philosophy and approach · chapters 1–6
The four design pillars and the criteria that flow from them.
Applying the approach · chapters 7–10
The four-stage design process, difficult sites, roads and urban areas.
Technical detail · chapters 11–23
A chapter per component: rainwater harvesting to ponds and wetlands.
Supporting guidance · chapters 24–36
Hydraulics, infiltration, water quality, materials, construction, maintenance, costs.
Appendices A–C
Glossary, the design and maintenance checklists, and a full worked design example.
The thirteen component chapters in Part D all follow the same template: general description, selection and siting, hydraulic design, treatment, amenity, biodiversity, materials, construction and maintenance. That repetition is what makes C753 work as a reference, because you can open the swale chapter cold and know exactly where the answer sits. Part E is where the numbers live, including the infiltration design methods that a BRE 365 soakage test feeds.
Key design criteria in C753
The numbers most people open the Manual for sit in chapter 3, which sets three water quantity standards, and chapter 24, which supplies the calculation methods behind them. C753 is careful to call these "standards of good practice" and notes that local planning documents or national standards may take precedence, but LLFAs treat them as the starting point for any drainage strategy.
| Standard | What it requires |
|---|---|
| 1. Runoff volume | No runoff leaves the site for the majority of small rainfall events (Interception, with about 5 mm normally achievable), and the 1 in 100 year, 6 hour runoff volume is kept to greenfield levels. Where that cannot be achieved, the excess (long-term storage) is discharged at 2 l/s/ha or less. |
| 2. Peak runoff rate | Peak flows constrained to greenfield rates for both the roughly 1 in 1 year event, which protects the receiving watercourse from erosion, and the 1 in 100 year event. On previously developed sites, rates are reduced to greenfield wherever possible, with betterment of at least 30% considered a minimum. |
| 3. On-site flood risk | No flooding on site for events up to the design standard of service, normally a 1 in 30 year minimum, unless an area such as a car park is deliberately designed to flood. Properties are protected in the 1 in 100 year event, with floor levels at least 300 mm above the predicted flood level and exceedance flows routed safely. |
Two allowances thread through all of these: the design rainfall includes an uplift for climate change, and the impermeable area includes an allowance for urban creep, the gradual paving-over of gardens and driveways after occupation. Chapters 4 to 6 set the equivalent criteria for water quality, amenity and biodiversity, so the four pillars each carry design tests of their own rather than sitting as aspirations.
Is C753 still the current SuDS Manual in 2026?
Yes. As of July 2026 there is no second edition and no announced replacement: C753 remains the current SuDS Manual, and Lead Local Flood Authorities across England and Wales still cite it in their standing advice. The PDF issued today is Version 6, incorporating minor amendments from 2016, 2018 and 2019; the substance of the 2015 text stands.
That longevity was designed in. David Balmforth, who chaired the project steering group, closed his foreword with a prediction that has aged rather well:
They have delivered a master-piece of technical guidance that will last for many years. I thoroughly recommend it to you.
David Balmforth, chairman of the C753 project steering group, writing in the Manual's foreword
CIRIA's effort since 2015 has gone into companion material rather than a rewrite: a frequently asked questions document, refreshed design, construction and maintenance checklists, the Simple Index Approach spreadsheet for water quality design (now at version 26), and, in September 2025, C823F, a separate guide to getting SuDS right from the start of a development. What has changed substantially is the policy sitting around the Manual, which is where the 2025 National Standards come in below.
How to download the SuDS Manual (C753) for free
The full Manual has been free since publication; the £250 price applies only to the printed volume. The free PDF carries the reference C753F (the F stands for free) and CIRIA hosts it directly:
- Go to CIRIA's free publications page for The SuDS Manual (C753F).
- Register for a free CIRIA account, or log in if you already have one.
- Download the PDF: a single file of roughly 15 MB covering all 968 pages.
susdrain, the CIRIA-run SuDS knowledge hub, hosts the companion FAQs, checklists and SIA tool alongside it. Treat third-party copies with caution; older files still circulate, and downloading from CIRIA is the only way to be certain you have the current version.
How the Manual is used in a planning application
You will never be asked to submit the SuDS Manual itself. What happens instead is that the documents you do submit are judged against it. In our experience it surfaces at four points:
- Drainage strategies: LLFAs expect runoff rates, attenuation storage and the treatment train to follow C753 methods, and many local validation checklists and SuDS proformas cite it by name.
- Flood risk assessments: the surface water and drainage sections of a site-specific FRA lean on C753's criteria for interception, attenuation and exceedance.
- The design stages: chapter 7 sets out a four-stage process (strategic objectives, conceptual design, outline design, detailed design) that maps neatly onto planning milestones from outline consent through reserved matters.
- Discharging conditions: pre-commencement drainage conditions typically call for a detailed scheme plus a whole-life maintenance plan, which is exactly what the Appendix B checklists were written for. Unda's discharge of drainage conditions work leans on them constantly.
When an LLFA objection says a drainage strategy "does not accord with the SuDS Manual", it means C753. There is no other manual it could mean.
C753, the 2025 National Standards and C823F
Defra published new National Standards for Sustainable Drainage Systems on 19 June 2025 (updated 30 July 2025), the first substantial refresh of national SuDS policy in a decade. They did not replace the SuDS Manual; the two documents do different jobs. The standards set what a scheme should achieve, including the five-tier discharge hierarchy and the requirement to intercept the first 5 mm of rainfall. C753 remains the how: the design methods, component detail and calculations that get a scheme to those outcomes.
| Document | Published | Job it does | Status |
|---|---|---|---|
| The SuDS Manual (C753) | November 2015 (now Version 6) | How to design: methods, components, calculations, maintenance | Industry guidance; the accepted technical benchmark |
| National Standards for SuDS | 19 June 2025 | What to achieve: discharge hierarchy, interception, flow control, quality, amenity, biodiversity | Non-statutory Defra standards, applied through planning |
| C823F: Getting SuDS right from the start | September 2025 | When to act: SuDS decisions from land purchase to masterplan | Free advisory CIRIA guide |
None of this is statutory in England. Schedule 3 of the Flood and Water Management Act 2010, which would make SuDS approval mandatory, remains uncommenced, a position a House of Commons briefing confirmed again in February 2026. Wales commenced it in 2019. Until England follows, the standards and the Manual are enforced the same way: through the planning system, by LLFAs who know both documents well.
What the SuDS Manual means for your development
You do not need to read 968 pages; that is your drainage consultant's job. What matters for a planning application is that the drainage strategy shows its working in C753 terms: greenfield runoff comparisons, storage sized to the right events with climate change allowances, a treatment train justified by the Simple Index Approach, and a maintenance plan someone will actually own. Strategies drafted that way tend to pass LLFA review first time. Strategies that treat SuDS as a tank under the car park attract objections.
The Manual's own message is the one worth keeping: SuDS designed early and designed well add value to a development. Drainage bolted on at the end costs plots, time and goodwill.
Unda prepares surface water drainage strategies designed to C753 and the 2025 National Standards, from first feasibility advice through to discharging conditions. If your site needs one, or an LLFA has pushed back on the one you have, get in touch.
Frequently asked questions
What is the Simple Index Approach (SIA)?
The water quality design method in chapter 26 of C753. Each land use is given pollution hazard indices for sediments, metals and hydrocarbons, and each proposed SuDS component carries mitigation indices; the scheme passes when the mitigation provided meets or exceeds the hazard. LLFAs routinely ask to see the SIA table in a drainage strategy, and CIRIA maintains a free spreadsheet tool for the calculation, currently at version 26.
Is the SuDS Manual mandatory?
No. C753 is industry guidance and nothing in law compels an applicant to follow it. In practice the distinction matters less than it sounds: national planning policy expects major developments to incorporate sustainable drainage, LLFAs are statutory consultees on surface water, and they assess schemes against C753 methods. A strategy that departs from the Manual needs a technical justification the reviewing officer will accept, so non-statutory should never be read as optional.
Does C753 apply in Scotland, Wales and Northern Ireland?
It was written for the whole of the UK, and its funders included SEPA, the Northern Ireland Environment Agency and the Welsh Government. The design methods are used in all four nations. The legal frameworks differ: Wales operates a statutory SuDS Approving Body regime with its own national standards sitting above the Manual, while in Scotland SEPA's regulatory guidance applies alongside it.
How is C753 different from the 2007 manual (C697)?
C753 was a rewrite rather than an update. The 2015 team restructured the document for a much wider audience, taking in planners, landscape architects, ecologists and developers as well as drainage engineers, and threaded the four pillars through every component chapter instead of treating amenity and biodiversity as afterthoughts. It also added guidance on planning for extreme rainfall and exceedance, urban design typologies, and far more material on costs, maintenance and community engagement.
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