The Ultimate Guide to Subsurface Drainage Solutions for Your Garden

French drain and soakaway crate garden drainage system
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Proper drainage is crucial for maintaining the health and beauty of your garden. Poor drainage can lead to waterlogging, soil erosion, and an unhealthy environment for plants. 

In this guide, we’ll explore the best subsurface drainage solutions for your garden, including French drains, soakaways, permeable paving, and drainage pumps. These methods will help you manage surface water, conserve water, and maintain a sustainable and attractive garden design.

French Drains

French drains are an effective garden drainage solution that helps manage groundwater and prevent waterlogging. They consist of a trench filled with gravel or rock and a perforated pipe that redirects water away from your garden.

French drain and soakaway crate garden drainage system


  • French drains help prevent soil erosion and protect plant roots from excess water.
  • They can be easily integrated into your existing garden design.
  • They can help manage surface water and reduce the risk of flooding.

How to install a French drain:

  1. Identify the problem area in your garden where water tends to accumulate.
  2. Dig a trench at least 18 inches deep and 6 inches wide.
  3. Line the trench with geotextile membrane to prevent soil from clogging the drain.
  4. Place a 2-inch layer of gravel in the trench.
  5. Install an 80mm perforated PVC pipe, don’t forget end caps to stop the stones getting into the pipe.
  6. Cover the pipe with more gravel, filling the trench to within 2 inches of the surface.
  7. Fold the landscape fabric over the gravel and backfill the trench with soil.
  8. Finish by adding grass seed or plants on top of the soil.


Soakaways are another effective drainage solution for gardens, designed to disperse water into the surrounding soil. They are essentially underground pits filled with rubble or other porous materials that allow water to infiltrate the ground.

Square hole in garden filled with drainage cubes


  • Soakaways help manage surface water and reduce the risk of flooding.
  • They promote natural water infiltration and can help recharge groundwater.
  • They require little maintenance once installed.

How to install a soakaway:

  1. Identify a suitable location for the soakaway, at least 5 metres from any building foundations and away from areas with high water tables.
  2. Dig a hole that is large enough to accommodate the water flow from the area you wish to drain.
  3. Line the hole with geotextile fabric to prevent soil from entering the soakaway.
  4. Fill the hole with rubble, coarse gravel, or drainage cubes, ensuring there is a 100mm layer at the base.
  5. Connect a perforated pipe to the soakaway to direct water into it. Make sure the pipe slopes slightly towards the soakaway to encourage proper drainage.
  6. Cover the soakaway with more geotextile fabric and backfill the area with soil.
  7. Landscape the area to blend in with your garden design.

For more information on installing a drainage cube soakaway, check out this article.

Permeable Paving

Permeable paving is an innovative solution for managing rainwater and surface water in your garden. It consists of paving materials designed to allow water to infiltrate the ground, rather than running off and causing erosion or flooding.

concrete block paving square


  • Permeable paving reduces the risk of flooding and surface water runoff.
  • It contributes to a more sustainable and eco-friendly garden design.
  • It can be visually appealing and add value to your property.

How to install permeable paving:

  1. Choose a suitable permeable paving material, such as permeable concrete, porous asphalt, or permeable pavers.
  2. Excavate the area where you plan to install the paving, removing any existing grass, soil, or hardscape materials.
  3. Install a geotextile fabric at the base of the excavated area to prevent soil mixing with the layers above.
  4. Create a sub-base layer using compacted crushed stone or gravel. This layer should be at least 6 inches thick to provide adequate support and drainage.
  5. Install an optional layer of finer aggregate, such as sand or small gravel, to provide a smooth and level surface for the permeable paving material.
  6. Lay the permeable paving material, ensuring that joints or gaps between the pavers are filled with a permeable aggregate or sand.
  7. Compact the surface with a plate compactor or roller to create a stable and even surface.
  8. Landscape the surrounding area to blend with your garden design.

Drainage Pumps

Drainage pumps are a powerful solution for gardens with persistent waterlogging issues or areas with high water tables. They are designed to pump excess water away from your garden, ensuring a healthy and dry environment for your plants.


  • Drainage pumps can handle large volumes of water and are suitable for gardens with severe drainage issues.
  • They can be used in conjunction with other drainage solutions, such as French drains or soakaways, to provide comprehensive water management.
  • They can help prevent damage to your garden’s infrastructure, such as pathways or foundations, by removing excess water.

How to install a drainage pump:

  1. Choose a suitable drainage pump based on your garden’s needs, considering factors such as power, flow rate, and lift capacity. A submersible pump is a popular choice for garden applications.
  2. Identify a suitable location for the pump, preferably in a low-lying area where water tends to accumulate. Ensure that the pump is positioned within reach of a power source and a suitable discharge point.
  3. Dig a sump or pit for the pump, deep enough to accommodate the pump and any additional components, such as a float switch or check valve.
  4. Install a sump liner or sump basin to house the pump and prevent soil from entering the system.
  5. Place the pump in the sump, following the manufacturer’s instructions for proper installation and wiring.
  6. Connect a discharge pipe to the pump, running it to a suitable discharge point, such as a storm drain, soakaway, or French drain.
  7. Test the pump to ensure proper operation and adjust any settings as necessary.
  8. Cover the sump with a secure lid to prevent debris and animals from entering the system. Landscape the area to blend in with your garden design.

To conclude, proper drainage is essential for maintaining a healthy and beautiful garden. By choosing the right subsurface drainage solution, such as French drains, soakaways, permeable paving, or drainage pumps, you can prevent waterlogging, soil erosion, and protect your plants and garden infrastructure. Each of these solutions offers unique advantages, and understanding their benefits will help you make an informed decision for your garden’s needs.

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