French drain installation creates a gravel-filled trench containing a perforated pipe that collects subsurface water and conveys it away to a soakaway, watercourse or surface water sewer. The trench is lined with geotextile to prevent fine soil from clogging the gravel, and the pipe is laid to a fall to ensure free draining. French drains are widely used in London gardens with high water tables, alongside basement walls, and around the perimeter of sports pitches and patios. They will not address sewage or roof runoff and must not be connected to foul drains. Design follows BS EN 12056 and Building Regulations Part H3 where relevant, and large schemes near buildings should consider potential effects on ground stability.
French drain installation
Construction of a perforated pipe and gravel trench to collect groundwater.
