A French drain, drain tile, perimeter
drain or land drain is a trench covered with gravel or rock that redirects
surface and groundwater away from an area. A French drain can have hollow pipes along the bottom (see images) to
quickly vent water that seeps down through the upper gravel or rock. French drains are common drainage systems, primarily
used to prevent ground and surface water from penetrating or damaging building foundations. Alternatively, the French drain
technique may be used to distribute water, such as that which flows from the outlet of a typical septic tank sewage treatment
system. French drains are also used behind retaining walls to relieve ground water pressure.
How to Install a French
Drainage system using perforated drain pipe
First
determine if you have a place where the drain pipe can be daylighted while using gravity to drain the pipe
Mark & Measure the length of the pipe run
- Excavate a trench at least 6"
wide & starting 24" deep depending on your situation
- Excavte the trench & make
sure you have a good drop for the water to flow by gravity
- Line the trench with Landscape fabric
on the bottom & up the sides of the trench leaving enough to overlap the top & ends after the pipe is installed
- Install 2" of pea gravel paying careful attention to the grade
- Fit a filter
sock over the perforated drain pipe & install the pipe with the holes down, This will prevent dirt from entering
the holes
- Finish covering the pipe with pea gravel to within 4" to the surface &
cover with the Landscape fabric
- Now install coarse sand on top & then your Sod, Grass seed
or crushed granite or any other groundcover
