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, you will need
to have a slope of 1/8" or 1/10 per ft. of pipe run
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
All Photos of work by Landscape Drainage Solutions Inc.