The free diy home improvement guide with answers to your questions on a wide range of do it yourself projects.


French Drain

Anyone who has the problem of a water logged garden will know how difficult it can be to direct water away from the areas where it tends to pool. You are left with muddy patches on your grass and water close to your home which can result in damp entering your house. Installing a French drain or a soakaway is the perfect solution to this problem and will result in a garden in which puddles of water are a thing of the past.

A French drain is simply a trench which is dug in your garden to allow water to be directed away from your home or other areas where it builds up. It is never a good idea to allow rainwater to pool close to any building as it can seep into your woodwork or bricks and cause damp and rotting.

A French drain should never be dug deeper than the foundations of the house and it should slope away from the house at a 45 degree angle to allow the water to fall away naturally. The end of the drain should be in an area where the water can more easily soak away. This may involve digging a soakaway.

Building a French drain

  • Dig a trench around 15cm wide and deep enough to allow the correct angle to be achieved. Line it with ground sheeting which will allow water to pass through, but not soil particles or vegetation. This sheeting is available at garden centres and can also be used under gravel paths to prevent weeds growing through.
  • Fill the trench with stone or broken bricks. Leave a gap at the top, wrap the sheeting over and backfill with topsoil. This can then be covered with the usual paving, gravel or grass.
  • Dig a soakaway at the end of the French drain. This is similar to the drain, but is a larger and deeper hole and is filled with rubble. The water should be directed along the drain into the hole where it will soak away over a few hours. A soakaway should be built at least 5 metres from your house and in an area which does not suffer from water drainage problems.

If you would rather use a pipe to direct the water away, a type of perforated pipe designed for this use can be bought from garden centres. This pipe works in a similar way to the lining fabric by allowing water to filter out, but leaving behind the silt and rubble. This isn't really a French drain but is commonly referred to as a land drain.