Drainage Strategy for Planning: The Complete Guide

What Is a Drainage Strategy?

A drainage strategy is a technical document that sets out how surface water runoff and foul water from a proposed development will be collected, managed, treated, and discharged. It is a core component of most planning applications and is the primary means by which a developer demonstrates that the proposed development will not increase flood risk downstream, will manage surface water sustainably, and will connect appropriately to existing drainage infrastructure.

The drainage strategy sits at the intersection of several disciplines: civil engineering, hydrology, environmental management, and planning policy. It must satisfy the requirements of the Lead Local Flood Authority (LLFA), the local planning authority (LPA), the Environment Agency (where applicable), and the sewerage undertaker (the water company responsible for the local sewer network). Getting any one of these stakeholders offside can delay or derail a planning application.

For developers, the drainage strategy is not merely a technical exercise to be ticked off a list. It is a document that directly influences site layout, ground levels, open space provision, and construction costs. A drainage strategy designed early and integrated with the masterplan can reduce infrastructure costs, create amenity value, and streamline the planning process. A drainage strategy designed as an afterthought — retrofitted to a fixed layout — almost always costs more, takes longer, and attracts objections.

When Do You Need a Drainage Strategy?

Planning Application Stage

A drainage strategy is required for virtually all major planning applications in England and Wales. The triggers are:

• Major development: 10 or more dwellings, or residential development on a site of 0.5 hectares or more, or non-residential development with 1,000 square metres or more of floor space, or development on a site of 1 hectare or more. For all of these, the LLFA is a statutory consultee and will expect a drainage strategy.
• Sites in areas of known surface water flood risk: Even for minor development, if the site falls within an area identified on the Risk of Flooding from Surface Water (RoFSW) mapping, the LPA may require a drainage strategy.
• Sites in Critical Drainage Areas (CDAs): Where the Environment Agency or LLFA has designated a Critical Drainage Area, a drainage strategy may be required for smaller developments.
• Local plan policies: Many LPAs have adopted local policies that require drainage strategies for developments below the major threshold, particularly in flood-sensitive areas.

In practice, if you are submitting a planning application for anything other than a single dwelling or a minor extension, you should assume that a drainage strategy will be required.

Outline vs Full Application

The level of detail required varies with the application stage:

• Outline application: A drainage strategy at outline stage provides a conceptual framework — demonstrating that the site can be drained sustainably, identifying the likely discharge route and rate, and confirming that sufficient space exists for SuDS features and attenuation. It does not need to include pipe-by-pipe design.
• Reserved matters or full application: At this stage, the LLFA expects a detailed drainage strategy with hydraulic modelling, SuDS feature sizing, and a clear demonstration that the scheme works for the proposed layout. This is typically the stage at which MicroDrainage or InfoDrainage modelling is prepared.
• Discharge of conditions: Even where a drainage strategy is approved at full application stage, planning permissions almost always include a pre-commencement condition requiring the submission of a final detailed drainage scheme. This must include construction-level detail: pipe sizes, invert levels, manhole schedules, SuDS feature dimensions, and a maintenance and management plan.

What a Drainage Strategy Includes

A comprehensive drainage strategy for a planning application covers the following elements.

Site Assessment and Existing Drainage

The strategy begins with an assessment of the existing site conditions:

• Topography: Ground levels and natural fall across the site, determined from topographic survey or LiDAR data. The natural fall dictates the direction of surface water flow and the location of low points where water will accumulate.
• Existing drainage infrastructure: Identification of any existing sewers, drains, culverts, or watercourses on or adjacent to the site, using asset plans from the water company, historical mapping, and site survey.
• Geology and ground conditions: A review of British Geological Survey mapping and, where available, site investigation data to establish whether the ground is likely to support infiltration.
• Groundwater levels: High groundwater can preclude infiltration and affect the design of below-ground attenuation features.
• Existing impermeable area: For brownfield sites, the existing impermeable area is a critical input — it establishes the baseline against which betterment (a reduction in runoff) can be demonstrated.

The Drainage Hierarchy

Every drainage strategy must demonstrate compliance with the drainage hierarchy, as set out in Planning Practice Guidance and reinforced by the Non-Statutory Technical Standards for Sustainable Drainage Systems. The hierarchy is:

1. Discharge to ground (infiltration) — the preferred option
2. Discharge to a surface water body (watercourse)
3. Discharge to a surface water sewer
4. Discharge to a combined sewer — the last resort

The drainage strategy must work through the hierarchy sequentially, providing evidence at each stage to justify moving to the next option. This is not a formality. LLFAs reject drainage strategies that skip steps or provide inadequate justification. The most common rejection reason, by a considerable margin, is the absence of infiltration test data.

Infiltration Testing

If the site geology suggests that infiltration may be feasible — permeable soils such as sands, gravels, chalk, or sandstone — the drainage strategy must be supported by BRE365 soakaway test results. BRE Digest 365 is the accepted standard for infiltration testing in England and Wales, and the results determine whether infiltration-based SuDS features (soakaways, infiltration basins, permeable paving draining to the subbase) can be used.

The test involves excavating trial pits to the proposed soakaway invert depth, filling them with water three times, and recording the rate at which the water level falls. The infiltration rate (expressed in metres per second) determines the feasibility and sizing of infiltration features.

Key points for infiltration testing within a drainage strategy:

• Test at the right locations. Tests must be carried out at or close to the proposed SuDS feature locations, not at arbitrary points on the site.
• Test at the right depth. The test depth must correspond to the proposed invert level of the infiltration feature.
• Multiple tests are usually needed. A single test is rarely sufficient for a development site. LLFAs expect tests across the site to capture any variation in ground conditions.
• Record groundwater levels. If groundwater is encountered during excavation, this must be recorded. A minimum of 1 metre clearance between the base of an infiltration feature and the highest recorded groundwater level is the standard requirement.
• Contamination considerations. On brownfield sites, infiltration may be ruled out if the ground is contaminated and infiltration could mobilise pollutants into groundwater. This must be supported by evidence from the Phase 1 desk study or Phase 2 site investigation.

Where infiltration rates are too low (typically below 1 x 10^-6 m/s), the strategy moves to the next level of the hierarchy. Where rates are marginal, partial infiltration may be feasible — using infiltration features for a proportion of the runoff while discharging the remainder to a watercourse or sewer.

Surface Water Drainage Design

The core of the drainage strategy is the surface water drainage design. This sets out how rainfall falling on the developed site will be collected, stored, treated, and discharged at an acceptable rate.

Greenfield Runoff Rates

For greenfield sites, the LLFA will require that post-development discharge rates are limited to the greenfield runoff rate — the rate at which the undeveloped site would naturally discharge surface water. This is calculated using one of two accepted methods:

• IH124 (Institute of Hydrology Report 124): The traditional method, widely used for smaller sites. It estimates the mean annual flood flow (QBAR) based on site area, soil type, and annual rainfall.
• FEH Statistical Method (Flood Estimation Handbook): The more detailed approach, required by some LLFAs and generally preferred for larger sites. It uses the FEH web service to derive greenfield runoff rates based on catchment descriptors.

Both methods produce a rate in litres per second (l/s) that becomes the maximum permitted discharge from the site. Many LLFAs now require that discharge rates are limited to the QBAR greenfield rate for all events up to and including the 1 in 100 year storm, though some accept higher rates for rarer events.

For brownfield sites, the LLFA typically requires a reduction in discharge compared to the existing situation. Where the existing discharge rate is unknown, a pragmatic approach is to calculate what the greenfield rate would be and use that as the target, or to demonstrate a percentage reduction from the estimated existing rate.

Attenuation Storage

Because the development increases the proportion of impermeable surface (roofs, roads, hardstanding), the volume of runoff generated during a storm event increases. The difference between the volume generated by the developed site and the volume that can be discharged at the permitted rate must be stored temporarily on site. This is attenuation.

Attenuation storage is designed to manage the critical storm event — typically the 1 in 100 year rainfall event with a climate change uplift. The current climate change allowances for peak rainfall intensity range from 20% to 45% depending on the epoch and vulnerability classification (see our climate change allowances guide).

Attenuation can be provided through a range of features:

• Below-ground geocellular tanks (crate systems): High storage volume in a small footprint, suitable for constrained sites. However, they provide no water quality treatment, amenity, or biodiversity benefit, and most LLFAs prefer above-ground solutions.
• Below-ground oversized pipes: A cost-effective alternative to geocellular tanks on linear sites.
• Above-ground detention basins: Dry basins that fill during storm events and drain down afterwards. They provide attenuation, treatment, and amenity value, and are preferred by LLFAs.
• Ponds and wetlands: Permanent water features with additional flood storage volume above the normal water level. They deliver excellent water quality treatment and biodiversity value.
• Permeable paving sub-base storage: The void space within the granular sub-base of permeable paving provides significant storage volume while serving a dual function as a trafficable surface.
• Swales: Shallow grass-lined channels that convey and temporarily store water. They provide treatment and amenity value and are well-suited to road edges and open spaces.

The hydraulic design of the attenuation system is carried out using industry-standard software such as MicroDrainage (Innovyze) or InfoDrainage (Autodesk). The model simulates a range of storm durations at the design return period (1 in 100 year plus climate change) to identify the critical storm — the duration that generates the maximum storage volume. The attenuation features are then sized to accommodate this volume while restricting the outflow to the permitted discharge rate via a flow control device (typically a hydrobrake, orifice plate, or vortex flow control).

Exceedance Management

No drainage system is designed to cope with every possible rainfall event. The drainage strategy must demonstrate what happens when a storm exceeds the design capacity — where does the water go? This is exceedance management, and it is a non-negotiable requirement of most LLFAs.

Exceedance management involves:

• Identifying overland flow routes for storms exceeding the 1 in 100 year plus climate change event
• Demonstrating that exceedance flows are directed away from buildings and towards safe areas (open space, roads, designated flood routes)
• Ensuring that exceedance does not cause flooding to properties on or off the site
• Showing flood routing on a site plan with finished floor levels to demonstrate safe thresholds

Foul Water Drainage

While surface water receives most of the technical attention, the drainage strategy must also address foul water disposal. For most developments, foul water will discharge to the public foul sewer via a gravity connection. The strategy should confirm:

• The proposed foul water connection point and the route of the foul drainage network across the site
• Capacity confirmation from the sewerage undertaker (the water company). A pre-development enquiry to the water company should confirm whether the receiving sewer and downstream treatment works have capacity to accept the additional foul flows from the development.
• Whether a pumping station is required. If the site topography does not allow gravity drainage to the connection point, a pumping station may be needed. This adds cost and introduces a maintenance liability that must be addressed in the strategy.
• Adoption arrangements. Foul sewers are typically adopted by the water company under a Section 104 agreement (in England and Wales). The strategy should confirm the proposed adoption route.

Where no public foul sewer is available — typically in rural locations — the drainage strategy must address alternative foul water treatment, such as a package treatment plant or septic tank, in accordance with Building Regulations Part H and the Environment Agency’s General Binding Rules or environmental permit requirements.

SuDS Integration

Modern drainage strategies are expected to deliver more than just flood risk management. The National Planning Policy Framework, the CIRIA SuDS Manual (C753), and the Non-Statutory Technical Standards all require that surface water drainage systems provide multiple benefits: water quantity management, water quality treatment, amenity, and biodiversity.

The drainage strategy must demonstrate how SuDS features have been integrated into the development design and how they deliver against these four pillars:

Water Quantity

This is the attenuation function described above — restricting discharge to greenfield rates and managing the critical storm event. SuDS features such as permeable paving, swales, detention basins, and ponds all contribute to attenuation.

Water Quality

Surface water runoff from developed surfaces carries pollutants — sediment, hydrocarbons, heavy metals, nutrients, and litter. The drainage strategy must demonstrate that adequate water quality treatment is provided before runoff leaves the site.

The standard assessment method is the Simple Index Approach from CIRIA C753 (the SuDS Manual). This assigns a pollution hazard level to each surface type (residential roofs are low hazard; car parks are medium; commercial yards are high) and a mitigation index to each SuDS treatment feature. The strategy must demonstrate that the total mitigation provided by the SuDS treatment train is sufficient to address the hazard.

In practice, this means providing at least two treatment stages for most runoff — for example, permeable paving followed by a swale, or a filter drain followed by a detention basin.

Amenity

SuDS features should contribute positively to the public realm. Swales along road edges, rain gardens in front gardens, detention basins designed as usable open space, and ponds that create focal points within a development all enhance the quality of the built environment. Many LLFAs now explicitly score drainage strategies on amenity provision and will push back on designs that rely solely on below-ground infrastructure.

Biodiversity

Well-designed SuDS features create habitat for wildlife — wetland planting in ponds and swales, wildflower meadows on detention basin slopes, and native hedgerow planting along filter strips. With the mandatory requirement for Biodiversity Net Gain (BNG) now in force for most developments, SuDS features that deliver habitat creation can help meet BNG obligations while serving a drainage function.

Design Standards and Regulations

A drainage strategy must comply with a matrix of national and local standards. The key documents are:

Building Regulations Approved Document H (Drainage and Waste Disposal)

Part H sets out the legal requirements for drainage of buildings. It establishes the drainage hierarchy (infiltration first), requires that surface water drainage systems are designed to manage rainfall up to the 1 in 100 year event, and specifies requirements for foul drainage, rainwater drainage, and wastewater treatment.

Non-Statutory Technical Standards for Sustainable Drainage Systems (Defra, 2015)

These standards set out the technical requirements that SuDS schemes must meet. Key standards include:

• S1: Surface water runoff rate from the developed site must not exceed the greenfield rate for the corresponding event
• S2: Volume control — where reasonably practicable, the drainage system should provide long-term storage to manage the additional volume of runoff from impermeable surfaces
• S3: Water quality — the drainage system must provide adequate treatment of surface water before discharge
• S4: Flood risk within the development — the drainage system must be designed to manage events up to the 1 in 30 year return period without any above-ground flooding, and manage events up to the 1 in 100 year plus climate change without flooding of buildings

Sewers for Adoption (Design and Construction Guidance for Developers)

Now formally replaced by the Design and Construction Guidance (DCG) published by Water UK in 2023, this document sets out the design standards for sewers and drainage infrastructure that will be adopted by the water company. It covers pipe sizes, gradients, materials, manhole spacing, and SuDS feature design standards for adoptable infrastructure. Any drainage infrastructure proposed for adoption under a Section 104 agreement must comply with these standards.

CIRIA C753 — The SuDS Manual

The definitive reference for SuDS design in the UK. Published by CIRIA (the Construction Industry Research and Information Association), C753 provides comprehensive guidance on the planning, design, construction, operation, and maintenance of SuDS. It is the standard against which LLFAs and water companies assess SuDS designs and is an essential reference for any drainage strategy.

Local Authority Standards

Each LLFA publishes its own local drainage guidance, which supplements the national standards. These can vary significantly between authorities. Some common variations include:

• Discharge rate requirements: Some LLFAs require greenfield QBAR rates for all events; others allow higher rates for rarer events or accept a flat rate of 5 l/s as the minimum.
• Climate change allowances: While the EA publishes national allowances, some LLFAs apply their own more conservative uplifts.
• SuDS expectations: Some LLFAs are prescriptive about requiring above-ground SuDS and will reject strategies that rely solely on below-ground attenuation. Others are more flexible.
• Water quality requirements: Some LLFAs require a formal Simple Index Approach assessment; others accept a qualitative description of treatment provision.
• Adoption expectations: Some LLFAs expect SuDS features to be adopted by a public body; others accept private management arrangements.

Understanding the local LLFA’s specific requirements before starting the drainage design is essential. At Aegaea, we maintain up-to-date knowledge of LLFA requirements across England and Scotland, and we tailor every drainage strategy to the relevant authority’s standards.

The Drainage Strategy Process

Step 1: Site Assessment and Data Collection

Before any design work begins, the drainage engineer collects the data needed to inform the strategy:

• Topographic survey of the site
• Water company asset plans (sewer records)
• British Geological Survey mapping
• BRE365 infiltration test results (or commissioning of tests)
• Environment Agency flood data (if relevant to the surface water strategy)
• Local authority drainage guidance and standing advice
• Pre-application discussions with the LLFA (for complex sites)
• Pre-development enquiry to the water company

Step 2: Establish Design Parameters

Using the collected data, the engineer establishes the key design parameters:

• Greenfield runoff rate (QBAR and higher return periods)
• Design storm return period and climate change allowance
• Infiltration rate (from BRE365 results)
• Discharge hierarchy — which option is appropriate
• Agreed discharge point and permitted rate
• Foul water connection point and capacity

Step 3: Conceptual Design

The engineer develops a conceptual drainage layout showing:

• Catchment areas for each drainage subcatchment within the site
• Proposed SuDS features and their approximate locations
• Attenuation feature locations and approximate volumes
• Discharge points and flow control locations
• Foul drainage routing
• Exceedance flow routes

This conceptual design should be developed in parallel with the site masterplan. The layout of roads, buildings, open spaces, and levels should be informed by the drainage requirements, not the other way around. Designing drainage around a fixed layout is one of the most reliable ways to increase costs and invite LLFA objections.

Step 4: Detailed Hydraulic Design

Using MicroDrainage, InfoDrainage, or equivalent software, the engineer models the drainage network in detail:

• Each pipe, swale, and SuDS feature is modelled with its dimensions and levels
• The critical storm duration is identified for each subcatchment
• Attenuation volumes are confirmed
• No flooding is demonstrated for the 1 in 30 year event
• Flooding is contained within acceptable limits for the 1 in 100 year plus climate change event
• Exceedance routing is verified

The model outputs form the technical evidence base for the drainage strategy and are submitted alongside the report.

Step 5: Report Preparation

The drainage strategy report brings together all of the above into a coherent document that addresses LLFA and LPA requirements. A well-structured report typically follows this format:

1. Introduction and site description
2. Planning policy context
3. Existing site conditions and drainage assessment
4. Drainage hierarchy assessment with infiltration test evidence
5. Proposed surface water drainage strategy
6. Attenuation and flow control design
7. Water quality assessment (Simple Index Approach)
8. Foul water drainage strategy
9. Exceedance management
10. Maintenance and management plan
11. Conclusions and recommendations
12. Appendices (hydraulic model outputs, infiltration test results, water company correspondence, drawings)

Step 6: Submission and Consultation

The drainage strategy is submitted as part of the planning application. The LLFA reviews it as a statutory consultee and provides comments to the LPA. Common outcomes include:

• No objection: The strategy meets all requirements. This is the target outcome.
• No objection subject to conditions: The strategy is acceptable in principle, but the LLFA requires further detail at the discharge of conditions stage — typically construction-level detail, a maintenance plan, or specific SuDS feature designs.
• Holding objection: The strategy has deficiencies that must be addressed before the LLFA can support the application. This triggers a round of revisions and resubmission.

A holding objection does not mean the application will be refused, but it does mean the planning decision is delayed until the drainage issues are resolved. Avoiding holding objections is a matter of getting the strategy right from the outset — understanding what the LLFA requires, providing the right evidence, and designing to the appropriate standards.

Discharge of Planning Conditions

Even where the drainage strategy is accepted at planning application stage, the planning permission will almost always include a pre-commencement condition requiring a detailed drainage scheme to be submitted and approved before construction begins. This is the discharge of conditions stage.

The discharge of conditions submission is more detailed than the planning application drainage strategy. It typically includes:

• Detailed engineering drawings: Plans, long sections, and cross sections showing pipe sizes, invert levels, manhole locations, SuDS feature dimensions, and construction details.
• Updated hydraulic model: The final model reflecting the as-designed drainage layout, demonstrating compliance with all design standards.
• SuDS feature design details: Construction-level drawings for each SuDS feature — permeable paving buildup, swale profiles, detention basin geometry, pond bathymetry, flow control chamber details.
• Maintenance and management plan: A document setting out who will maintain each drainage feature, how often, what maintenance activities are required, and how the maintenance will be funded in perpetuity. This is a critical document — LLFAs will not approve a discharge of conditions application without a robust maintenance plan.
• Section 104 application (if applicable): If the drainage infrastructure is to be adopted by the water company, the Section 104 application to the water company should be progressed in parallel with the discharge of conditions application.
• Verification plan: Some LLFAs require a verification plan that sets out how the as-built drainage system will be tested and verified to confirm it has been constructed in accordance with the approved design.

The discharge of conditions application is submitted to the LPA, which consults the LLFA. The LLFA reviews the detailed scheme and, if satisfied, recommends approval. The process typically takes 8-12 weeks from submission to approval, though this varies by authority.

It is essential to discharge the drainage condition before construction begins. Starting construction without discharging pre-commencement conditions is a breach of planning, and enforcement action can follow. This is not a theoretical risk — LPAs do pursue enforcement for breach of pre-commencement conditions, and the consequences can include stop notices and prosecution.

Costs

Drainage Strategy Preparation

Scope	Typical Cost	Notes
Small residential (10-30 units)	£2,000 - £4,000	Standard site, single outfall, straightforward SuDS
Medium residential (30-100 units)	£4,000 - £8,000	Multiple subcatchments, detailed SuDS design, hydraulic modelling
Large residential (100+ units)	£8,000 - £15,000+	Complex site, multiple phases, strategic SuDS features, extensive modelling
Commercial / mixed use	£5,000 - £12,000	Depends on site area, impermeable coverage, and water quality requirements

Associated Costs

Item	Typical Cost
BRE365 infiltration testing (3-5 trial pits)	£1,000 - £3,000
Water company pre-development enquiry	£0 - £500 (varies by company)
Topographic survey	£1,000 - £5,000 (depends on site size)
Discharge of conditions submission	£2,000 - £5,000 (in addition to planning stage strategy)
Section 104 application support	£2,000 - £5,000

These costs should be viewed in the context of the total development value. A well-designed drainage strategy that secures LLFA support at first submission saves weeks of delay and avoids the cost of redesign and resubmission. Conversely, a poorly designed strategy that attracts a holding objection can cost far more in programme delays than the difference in upfront fee.

Common Mistakes

Having reviewed and prepared drainage strategies for developments ranging from single plots to strategic land allocations of several thousand homes, we see the same mistakes repeatedly. Avoiding these will improve the quality of the submission and the likelihood of a smooth planning process.

1. No Infiltration Test Data

The single most common reason for LLFA objections. The drainage hierarchy requires infiltration to be considered first, and the LLFA requires BRE365 test data to demonstrate whether it is feasible. A desktop assertion that the site is on clay is not sufficient. Commission infiltration testing early — it should be one of the first site investigation activities.

2. Designing Drainage After Fixing the Layout

The drainage strategy should inform the site layout, not be retrofitted to it. When the layout is fixed before the drainage engineer is involved, common problems arise: insufficient space for attenuation, SuDS features squeezed into unusable corners, impractical pipe routes, and inadequate falls. Engage the drainage engineer at masterplanning stage, not after the layout is locked down.

3. Ignoring the LLFA’s Local Requirements

National standards provide the baseline, but each LLFA has its own local guidance, preferences, and expectations. A drainage strategy designed to generic national standards may not meet the specific requirements of the local authority. Check the LLFA’s published guidance before starting the design, and consider a pre-application discussion for complex sites.

4. Over-Reliance on Below-Ground Attenuation

Geocellular crate systems provide efficient storage in a small footprint, but they deliver no water quality treatment, no amenity value, and no biodiversity benefit. Most LLFAs now expect above-ground SuDS features — swales, rain gardens, detention basins, ponds — as part of the management train. A strategy that relies solely on pipes and crates is likely to be challenged.

5. Incorrect Greenfield Runoff Rates

Using the wrong method to calculate greenfield rates, applying rates for the wrong return period, or using a flat rate (such as 5 l/s per hectare) without justification are all common errors. The LLFA will check the rate calculation and will object if it is incorrect. Use the IH124 or FEH method as appropriate and present the calculation clearly.

6. Inadequate Exceedance Management

Designing for the 1 in 100 year plus climate change event is necessary, but the strategy must also address what happens when that event is exceeded. If the drainage system is overwhelmed, where does the water go? If the answer is “into people’s houses,” the strategy will not be approved. Exceedance flow routes must be identified and shown on a plan.

7. No Maintenance Plan

LLFAs will not approve a drainage strategy — particularly at discharge of conditions stage — without a maintenance and management plan. This must set out who maintains each feature, what maintenance is required, how often it is carried out, and how it is funded. For private SuDS features, this typically means a management company funded by a service charge.

8. Not Consulting the Water Company Early

If the drainage strategy proposes discharge to the public sewer network, the water company must confirm that capacity exists. Leaving this until after the strategy is submitted risks a late objection from the water company that could fundamentally change the drainage design. Submit a pre-development enquiry at the outset.

How Aegaea Helps

At Aegaea, drainage strategy is one of our core services. We prepare drainage strategies for developments across England and Scotland, from 10-unit residential schemes to strategic land allocations and complex commercial sites.

Our approach is straightforward:

• Early engagement: We get involved at masterplanning stage, ensuring the drainage strategy informs the site layout rather than fighting against it.
• Evidence-led design: We commission or review infiltration testing at the outset, ensuring the drainage hierarchy is properly evidenced from day one.
• LLFA knowledge: We maintain working relationships with LLFAs across the country and understand their specific requirements. Our strategies are tailored to the local authority, not generic.
• Integrated SuDS: We design SuDS schemes that deliver genuine multiple benefits — not just attenuation, but water quality treatment, amenity, and biodiversity value that strengthen the planning case.
• Full lifecycle support: From outline strategy through to discharge of conditions and Section 104 adoption, we support our clients through every stage of the drainage approval process.

If you need a drainage strategy for a planning application, or if you have a drainage condition to discharge, get in touch. We will scope the work, confirm the fee, and assign a dedicated engineer to your project from the outset.