How To Install A French Drain Or Dry Well

french drain dry well

Question: Someone told me a dry well or french drain installation will help with drainage in our landscape. What is it, and can we build it ourselves? Hollie, Ohio

Answer: Hollie, a downspout should be connected to an underground drainage system or sewer. If not, installing a french drain or dry well – will  help with the drainage problem.

Basically, a french drain is a shallow hole. It’s a primitive drainage system but useful for relieving soil of excess water.

French Drain Design, Construction and Installation

The design is simple. Drains can be of any size, according to circumstances. Construction can be crude and low in cost. If desired somewhat more elaborately and more expensive.

A very simple way of how to build and install a French Drain:

Dig a hole two to four feet deep and two to three feet in diameter. Make the sides vertical, and if the soil is very loose, line it with brick. Fill the hole to within six or eight inches of the top with large stones loosely packed.

Place a piece of hardware cloth (quarter-inch galvanized mesh) with roofing cement (tar) to prevent its rapid deterioration in contact with damp earth and put it over the stones.

Put a layer of gravel, sand and lime over the hardware cloth, and finally a layer of soil. The purpose of the mesh, gravel, sand and lime is to prevent the soil from packing down between the stones.

Before completing the installation, check the grade of the surrounding area. It grade should be pitched slightly towards the well.

Where To Locate The Downspout

It may be convenient to make the French drain close to the downspout. However you may need to locate it several feet away as in the case of basement waterproofing.

If it is not close to the water spill, a pipe should connect the downspout with the drain systems a few inches below the surface running into the well.

The drain trench can be:

  • Made of tile
  • A plastic drain tube
  • Perforated pipe
  • A simple sloping trench filled with stone

Basically, anything which the water can run into and through.

Dry wells are also useful for conserving moisture. For example, directing a flow of water towards a well in an area where there is too much sub-surface drainage. The held water over time, slowly seeps out through the walls of the well.

Possible Steep Walk Solution

drain could solve the issue of a puddle at the end of a steep walk, or at the bottom of a flight of steps.

Take note of old gardens. It is not uncommon to find in the lowest part a very small well. Under a flagstone walk, thick stones are placed directly on the soil, and not on a bed of sand or cinders.

Image: cogdogblog

Filed Under: Landscaping, LG, z-004

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