French Drain 101

Installation Steps

1. Plan & mark the route – Identify the problem area (pooling or soggy soil), select a suitable outlet where water will flow, and mark the trench line.

2. Dig the trench – Excavate a trench of appropriate depth (commonly 8 inches to 24 inches or more) and width, ensuring a consistent downward slope toward the outlet (often ~1% grade). 

3. Line the trench with filter fabric – Lay a water-permeable geotextile or filter fabric in the trench to keep soil and sediment from clogging the stone or pipe. 

4. Add a gravel base – Place a layer of crushed stone or gravel in the bottom of the trench to act as bedding for the pipe. 

5. Install the perforated pipe – Lay the perforated drainpipe along the trench on the gravel bed, with holes facing downward or as recommended, assuring proper slope toward the outlet. 

6. Cover pipe with gravel and wrap fabric – Cover the pipe with more gravel, then fold the filter fabric over the top (sometimes called “burrito wrap”) to encapsulate the gravel-pipe assembly. 

7. Backfill & finish surface – Fill the remaining trench with topsoil or sod/landscape material to restore the surface, ensuring water at grade drains away properly. 

Key Considerations

• Ensure the trench maintains a downward slope to guarantee drainage. 

• The filter fabric and gravel system help prevent clogging from soil and roots. 

• The outlet must drain to a safe discharge point (away from buildings/foundations) so water has somewhere to go.