Outdoor Drainage Solutions For Flood Prevention

dhcutilities
May 20
5 min read

We understand how important it is to protect homes, landscapes and infrastructure from the growing risk of flooding. With weather patterns shifting and urban areas expanding, the natural drainage processes that once managed rainfall are being disrupted. As impermeable surfaces such as concrete and tarmac dominate more of our built environment, water has fewer places to go—and that’s where sustainable drainage solutions come in.

This guide explores the causes of surface water flooding and outlines the full range of available outdoor drainage solutions. Whether you’re a homeowner tackling waterlogging in the garden or a property manager seeking commercial-scale flood defences, we’ll help you identify the most effective measures for long-term flood prevention.

Understanding the Problem: What Causes Outdoor Flooding?

Surface water flooding occurs when rain falls faster than it can drain away. Instead of soaking into the ground or flowing into drains, water collects on the surface as standing water, leading to puddling, soggy lawns or even structural damage. Unlike river or coastal flooding, surface water flooding is often localised and sudden, caused by:

Heavy rain over short or extended periods
Saturated or compacted soils with poor drainage
Urban developments with hard, impermeable surfaces
Blocked or poorly maintained existing drainage systems
Inadequate landscape grading or sloping

These conditions frequently affect residential gardens, driveways, patios and green spaces. Without intervention, excess water can damage foundations, smother vegetation, erode soil and raise insurance costs. Restoring or mimicking natural drainage processes is vital to relieve these issues and minimise the risk of flooding.

Outdoor Drainage Solutions: An Overview

Effective drainage and flood prevention require a combination of engineered infrastructure and soft landscaping. Known collectively as Sustainable Drainage Systems (SuDS), these solutions replicate natural drainage processes to manage the movement and quality of water at its source.

At DHC Utilities, we design and install SuDS for both residential and commercial clients. The following solutions address a variety of site conditions, from standing water in gardens to overflow on large-scale paved surfaces.

Permeable Surfaces: Reducing Runoff at the Source

Solid surfaces such as tarmac or paving prevent water from penetrating the soil. This leads to rapid water flows across surfaces, overwhelming drains and increasing surface water flood risk.

Better alternatives include:

Permeable paving – block systems with gaps or porous materials
Gravel with stabilisation mats – suitable for parking or paths
Resin-bound gravel – decorative yet functional, allowing infiltration
Bark or wood chippings – ideal for softer landscaped areas

These solutions allow rain to soak naturally into the ground, significantly helping to reduce surface runoff and replicate natural drainage processes. As a result, they help limit standing water, lower peak flows and reduce the risk of flooding.

Soakaways: Hidden Water Management

Soakaways are below-ground chambers that collect excess water from roofs, driveways or lawns and allow it to infiltrate the soil slowly. Typically made from geocellular plastic crates wrapped in geotextile fabric, they’re invisible once installed. A soakaway must be located at least five metres from buildings and sized according to the area it drains.

When connected to an existing drainage system or fed by a French drain, soakaways become a powerful way to prevent waterlogging and control water during heavy rain.

French Drains: Lateral Water Diversion

French drains are gravel-filled trenches with a perforated pipe that redirects water away from trouble spots. They're especially effective when rain falls on sloped lawns or where standing water builds up near structures.

By guiding excess water away and allowing infiltration en route, French drains reduce the load on the existing drainage system and mimic natural drainage processes.

Rain Gardens: Soak and Filter

A rain garden is a shallow, planted basin designed to slow and capture runoff. It receives water flows from driveways, patios or roofs and uses layered soil and deep-rooted plants to promote infiltration and filter pollutants.

This soft landscaping solution:

Manages excess water before it pools
Reintroduces biodiversity
Visually enhances outdoor spaces

Rain gardens are perfect for areas affected by waterlogging and serve as a living buffer against heavy rain, supporting local ecology while reducing the risk of flooding.

Green Roofs: Natural Absorption at Roof Level

Green roofs use layered systems of waterproofing, drainage and vegetation to capture rainfall and release it slowly through evaporation and transpiration.

These systems:

Minimise runoff from outbuildings or garages
Insulate properties
Support wildlife

By absorbing rainfalls and slowing water flows, green roofs mirror natural drainage processes and are ideal for dense urban spaces where ground-based solutions are limited.

Swales and Channels: Directing and Slowing Water

Swales are vegetated ditches that collect and guide surface runoff while allowing water to soak into the soil. When planted and maintained correctly, swales:

Filter pollutants
Reduce flow velocity
Prevent standing water and erosion

They’re particularly useful in developments where water flows across large areas during heavy rain, helping to reduce surface water impact and improve infiltration.

Retention and Detention Basins

These are large-scale basins designed to temporarily hold or permanently store excess water. They support natural drainage processes by slowing runoff and allowing gradual infiltration into the soil or release to waterways.

Retention ponds hold water year-round
Detention basins are dry until it rains

Both systems can be landscaped to support biodiversity and recreation while managing waterlogging and standing water across larger catchments.

Rainwater Harvesting and Water Butts

Rainwater harvesting captures rainwater from roofs using surface-level or underground storage tanks. Water butts are a simple domestic version, storing runoff from guttering systems for later garden use.

This strategy:

Reduces demand on sewers
Conserves mains water
Prevents excess water from overwhelming the existing drainage system

It’s particularly effective when paired with soakaways or permeable surfaces.

Flood Prevention Tips and Best Practices

In addition to installing drainage features, consistent maintenance and practical landscaping are key. Here’s how you can further reduce flood risk:

Keep gutters and drains clear of debris
Re-level or aerate compacted lawns
Amend soil with compost to enhance absorption
Use mulch to reduce surface runoff
Direct water flows away from structures using garden grading
Choose deep-rooted plants to absorb excess water

Together, these techniques reduce reliance on artificial systems and encourage natural drainage processes, helping to manage standing water, avoid waterlogging, and decrease the risk of flooding.

Legal and Planning Considerations

In England, planning laws and environmental regulations increasingly support the adoption of SuDS to manage excess water responsibly.

Be aware that:

Planning permission is required for impermeable surfacing over 5m² without drainage
Homeowners have a legal responsibility not to worsen flooding on neighbouring properties
Properties in high-risk zones may require a Flood Risk Assessment

Integrating natural drainage processes into your plans demonstrates compliance while supporting wider sustainability goals.

Let’s Solve Your Drainage Challenge

At DHC Utilities, we provide practical, long-lasting outdoor drainage solutions tailored to your property. Whether you're facing waterlogging, overwhelmed drains, or repeat flooding, we’ll deliver a system designed for performance and peace of mind.

07753 259 174