With our changing climate promising more frequent and heavier downpours of rain, new techniques are changing how we deal with a wetter environment. Our towns and cities have become denser and with more impermeable surfaces, surface water flooding is no longer an occasional nuisance; it’s an everyday design challenge. Sustainable Drainage Systems (SuDS) are a key tool in alleviating the problem of surface water runoff and increased flooding.
Their design is simple yet provides big benefits: SuDS manage the water where it falls, slow the flow, clean it, and make space for biodiversity and people. The technique combines good drainage, climate resilience and placemaking. This article explains the practical steps behind a robust drainage strategy and highlights UK projects where SuDS are already delivering benefits.
Why Sustainable Drainage Systems matter now
Storms are becoming more intense and unpredictable. Traditional piped drainage simply moves water off site faster, but that worsens the risk of flooding downstream and overloads sewers. Surface water drainage systems take a different approach: they mimic natural drainage systems processes (infiltration, storage, evapotranspiration) so rainfall is retained, cleaned and returned slowly to the landscape. Well-designed SuDS reduce flood peaks, recharge groundwater supplies, improve water quality, cool heat islands in urban areas and create habitat for wildlife, all at once.
The government’s UK national standards for SuDS (June 2025) formalises these expectations for England and signals that SuDS are now expected design infrastructure for flood risk management, not an optional extra. Well-designed surface water management schemes can deliver many environmental benefits and SuDS can also contribute to biodiversity net gain (BNG) when sited appropriately in developments.
Green infrastructure
As SuDS work on a process of filtration, sedimentation and infiltration systems, if they are used alongside suitable vegetation and materials such as permeable pavement rather than impermeable surfaces during construction, they can improve water quality as well as creating viable habitats and green spaces. For example, a water retention basin can store water and provide wetland habitat. Areas around SuDS can be planted to create natural environments that support wildlife and deliver BNG as well as water management.
SuDs solutions: practical steps to manage surface water
A reliable drainage strategy is a sequence of evidence-based steps followed by a management train. Skip one step and you risk over-spending, planning delays, or SuDS that fail in operation.
Start with a high-quality site assessment and survey
A drainage strategy begins with gathering facts about the water environment at the earliest stages: topography, soil type and infiltration rates, groundwater levels, proximity to watercourses, existing drainage assets, foul sewers and any contamination constraints. Good practice is to follow a staged approach: desk-study (historic maps, upstream catchment), a walkover of the development site, and then intrusive testing (percolation tests, trial pits, groundwater monitoring). Local authority guidance and many SuDS Approving Bodies (SABs) expect thorough site investigation to justify chosen SuDS components.
Assess risk of flooding at multiple scales
Consider pluvial (surface water), fluvial (river), groundwater and sewer surcharge, urban drainage and flow rates. A site in an unsaturated zone may be safe for buildings but still generate runoff that worsens downstream flooding. Surface Water Management Plans (SWMPs) and catchment modelling help place the site in the wider drainage context, so the strategy doesn’t merely shift risk elsewhere. Leicester’s SWMP is a practical example of using modelling to target hotspots for managing surface runoff and guide local SuDS choices.
Follow the drainage hierarchy and take a natural approach
Start with infiltration capacity assessment (soakaways, swales) where soils allow; if not possible use attenuation (retention ponds, underground tanks, rainwater harvesting) and treatment stages for dirty water (bioretention, filter strips) to remove pollutants such as heavy metals and improve water quality before discharge. The government’s standards describe design expectations for flow control, water quality treatment and resilience, and they should be applied as the baseline.
Model waste water runoff and storage needs
Use hydraulic/hydrological modelling (e.g., FEH web service data on rainfall) to size storage volumes and demonstrate that post-development runoff won’t exceed agreed greenfield rates or cause downstream harm. Include climate change allowances (longer, heavier storms and rainfall events) in calculations; the new standards encourage resilience planning.
Design for multifunctionality
SuDS are most cost-effective when they provide multiple benefits: a swale that conveys water can also be a wildlife corridor; a detention basin can be an amenity pond and provide biodiversity benefits. Projects such as the Olympic Park repurposed surface water scheme turned flood infrastructure into public space features.
Plan adoption, maintenance and funding
Good design is wasted if SuDS are not maintained. At the planning stage, clarify ownership (local authority, water company, management company), maintenance schedules and long-term funding. Schedule 3 of the Flood and Water Management Act and local SABs shaped this governance landscape, and the 2025 national standards require clear maintenance accountability. A SuDS Management Plan is a formal document detailing how a system will be maintained.
Monitor, learn and adapt
Implement monitoring for flow, pollution and vegetation establishment, and be prepared to adapt management as sites settle or climate patterns shift. Retrofit examples often refine initial designs after the first year of storms. Evidence-sharing platforms like Susdrain collect operational lessons from UK sites.
Established UK projects demonstrating how SuDS work
Here are several UK projects that demonstrate different facets of SuDS delivery.
Dales Brow (Salford) – local retrofit, major ecosystem gains
Dales Brow, a small greenspace retrofitted with SuDS features by City of Trees and partners, shows how even tight urban spaces can be transformed. The scheme used rain gardens, swales and improved connection to the outfall to reduce local flooding and improve biodiversity within an urban neighbourhood: it also highlighted creative financing models for retrofit where conventional funding was limited. Local partnership and pragmatic maintenance plans were central to the project’s success.
Lamb Drove (Cambourne) – SuDS in residential development
Lamb Drove in Cambourne integrated SuDS from the outset on a one-hectare affordable housing development. Designers combined permeable surfaces, swales and detention features so runoff was managed on site, avoiding sewer surcharge and creating green amenity space for residents. The site is a useful demonstration of how small residential schemes can include biodiversity-rich SuDS without large land take.
Victoria Park Health Centre (Leicester) – compact site, smart infiltration
At Victoria Park Health Centre, a constrained urban plot used roof gardens, an infiltration basin and permeable pavement to manage run-off while adding biodiversity roof and environmental enhancement. The project emphasised early site testing: percolation tests confirmed infiltration was feasible, allowing simpler SuDS rather than buried tanks. The case shows how an upfront site survey can dramatically simplify long-term costs.
Olympic Park, London – SuDS at scale
The Queen Elizabeth Olympic Park used a range of features (attenuation ponds, swales, green roofs) to manage stormwater across a major regeneration area. Crucially in this sustainable development, the water features doubled as public realm – visible, accessible and biodiversity-rich – and proved that large developments can integrate SuDS into high-quality urban design.
Policy, approvals and regulation
SuDS are no longer just best practice; the policy environment is changing to make them standard practice. The National Standards for Sustainable Drainage Systems (June 2025) set non-statutory but nationally endorsed expectations for SuDS design, maintenance and operation in England: flow control, treatment performance, resilience and clear ownership pathways. Local authorities are updating guidance from the Environment Agency and SABs are increasingly active in approvals and adoption decisions. Many councils (for example, Central Bedfordshire and Surrey) have already signalled transitional arrangements as they align local practice with the new standards.
That means developers must: provide higher-quality site assessments; model to the new standards; and demonstrate sustainable development and long-term maintenance funding. The pay-off is fewer planning refusals, lower downstream flood risk and more resilient places.
Common roadblocks and how to negotiate them
- Space constraints: not every site has room for large ponds. The answer is a mix of smaller, distributed measures (green walls and roofs, permeable paving, street trees) and off-site storage where appropriate.
- Underground utilities and contamination: intrusive investigations early on identify constraints; often a hybrid approach (infiltration plus sealed storage) works.
- Maintenance uncertainty: resolve ownership before planning consent. Adoptable SuDS by councils or water companies is preferable, but when private maintenance companies are used, robust long-term contracts and sinking funds are essential. Guidance and templates exist via Susdrain and local authority resources.
The business case: why SuDS pay back
SuDS often show a positive benefit: cost ratio once co-benefits are included, resulting in fewer flood-damage claims, reduced sewer upgrade costs, higher land values, biodiversity and recreation benefits, and lower urban heat impacts. Reports for Greater Manchester and other regions have shown retrofit SuDS can create green jobs, save repair costs and improve public health – arguments that help secure blended funding from developers, councils and environmental funds.
Good design can create climate resilience
SuDS are a practical, multiservice answer to the problem of how to manage surface water: they reduce flood risk, clean dirty water, cool towns and create habitat. But they only work if they’re based on good site investigation, modelled to the right standards, designed as multifunctional assets and backed by clear long-term maintenance plans.
The new standards raise the bar. Developers who start with strong site surveys and a well-documented drainage strategy will not only meet planning expectations; they’ll deliver greener, safer and more attractive places that stand up to a wetter future.
If you’re a planner, developer or community group, start with a site survey and use the new standards and Susdrain case studies to shape a SuDS approach that’s fit to face whatever the weather has to throw at us.
