Your Guide to Garden Drainage

Drainage might not be the first thing you think about when designing your dream outdoor space. You’re much more likely to get excited about porcelain patios, stepping stone paths and beautiful flowers. However, without proper drainage, it’s difficult to keep all of these wonderful garden features looking lovely, especially in the rainy season. 

So, what types of garden drainage are there, which parts of your garden require drainage, and how do you go about installing it? 

What is Garden Drainage?

Garden drainage refers to the systems and methods used to manage water flow in garden and patio areas. Proper drainage prevents waterlogging, which can damage plants, soil, and paving. Without effective drainage, you risk unsightly puddles, slippery surfaces, and even structural damage to your landscaping.

Different Types of Garden Drainage

There are several types of drainage systems suitable for gardens, each catering to different needs.

Channel Drainage 

Channel drains, also known as linear drains, are sleek and discreet, seamlessly integrating with your paving. They efficiently collect and divert surface water, preventing pooling and potential slip hazards.

Installation requires precise planning and execution to ensure proper flow and avoid blockages.

Surface Drainage

This involves shaping the garden to direct water flow towards designated drainage areas. It’s ideal for general water dispersal across larger areas.

Subsurface Drainage

A system which uses pipes installed below the ground to remove excess water from the soil. It’s perfect for gardens prone to waterlogging.

Aggregate Drainage

Using porous materials, like gravel, aggregate drainage allows water to percolate through the soil and away from critical areas. This method helps maintain soil health and prevents erosion. It’s cost-effective and provides excellent natural drainage, ensuring a slip-free environment. However, it may require regular maintenance to prevent clogging and might not be suitable for all soil types.

Using a permeable reinforcement solution, like Ecogrid, can help to keep aggregates in place. 

French Drains

A popular choice, French drains are trenches filled with gravel and a perforated pipe, directing water away from problem areas. They’re effective in areas with heavy rainfall and can handle large volumes of water. However, installation can be labour-intensive, and they require maintenance to ensure the pipe remains unclogged.

Where Should Gardens Have Drainage?

Effective drainage should be implemented in areas prone to water accumulation, such as:

• Patios and Walkways: To prevent slip hazards and maintain the integrity of your paving.
• Planters and Raised Beds: To ensure plants aren’t waterlogged, promoting healthy growth.
• Lawn Edges: To avoid water pooling, which can lead to soggy, unusable lawn spaces.

How to Put Drainage in a Garden

Improving drainage involves a few key steps:

1. Assess Your Garden: Identify areas where water collects or drains poorly.
2. Plan Your Drainage System: Decide on the type of drainage that suits your garden’s needs—surface, subsurface, or aggregate.
3. Implement the System: Install the chosen drainage method, ensuring it connects seamlessly to existing drains or water outlets.

How to Install a Channel Drain

Channel drains are an efficient way to manage water flow on patios and driveways. Here’s how to install one:

1. Plan the Layout: Identify the lowest point where water collects and plan your drain installation accordingly.
2. Mark and Prepare the Trench: First, you’ll need to mark out the area for your trench. The trench should be wide enough to accommodate the channel drain with an additional 100 mm of space on each side for the concrete haunching. Next, dig the trench to the correct depth. The depth should be the height of the channel drain, plus an extra 50 mm for the bedding material, and a final 2 mm gap at the top to allow for a slight rise above the finished surface.
3. Lay the Bedding Material: Once the trench is dug, add a 50 mm layer of sand or gravel. This will serve as a stable base for the drain. Use a plate compactor to firmly compact this material, ensuring a solid foundation.
4. Assemble and Prepare the Drain: Before you place the drain in the trench, assemble the individual channel sections. If you need to cut a section to size, always do this at the end opposite to where your outlet will be. This helps ensure that the outlet connection remains a clean, factory-made fit.
5. Install the Drain: Start laying the drain sections in the trench from the lowest point, where it will connect to your main drainage system or soakaway. Work your way upwards, installing end caps as you go. The last piece of the channel drain should have its end cap installed before you lay it in the trench.
6. Connect to the Main Drainage: Connect your channel drain to the main drainage system or soakaway using a 110 mm pipe. Depending on your drain’s design, you can use either a special outlet moulding on the channel itself or the outlet on an end cap. After making the connection, pour a little water into the drain to confirm that it flows freely and the connection is secure.
7. Protect and Pour the Concrete: To prevent concrete from seeping into the drain and blocking the channels, cover all the grating with masking tape. This is a crucial step to ensure the drain functions properly after installation. Next, pour the concrete into the trench, ensuring it comes to a height of 2 mm above the top of the grate. This slight elevation helps with effective water runoff.
8. Cure the Concrete: Finally, allow the concrete to set and cure for at least 72 hours. During this time, avoid any foot traffic or heavy loads on the area to ensure the concrete cures properly and the drain is securely set in place.

Installing a French Drain for a Patio

1. Plan and Mark: Identify the area where water accumulates and mark the path for the drain, ensuring it slopes away from your patio.
2. Excavate: Dig a trench approximately 15-25 cm wide and 60 cm deep along the marked path.
3. Add Gravel Base: Lay a 5-10 cm layer of coarse gravel at the bottom of the trench.
4. Place Pipe: Position a perforated pipe on top of the gravel, ensuring the perforations face downwards.
5. Fill with Gravel: Cover the pipe with more gravel, filling the trench up to ground level.
6. Cover: Optionally, cover with decorative stones or turf for a seamless finish.
7. Cover: Top with soil or decorative gravel to integrate with the garden’s appearance.

At RF Paving, we provide high-quality paving solutions that complement your garden’s drainage needs. Our expertise ensures your outdoor spaces are not only visually stunning but also practical and enduring. Whether you’re a landscaper, architect, or homeowner, our offerings cater to all your paving and landscaping requirements.