A ditch in your backyard might look grotesque, but ditches play the important role of channeling water away from your yard to prevent flooding. Water can slowly carve a drainage ditch, but some home builders dig ditches to improve drainage away from the home. You can't simply back-fill the ditch with soil because this could cause flooding in your and your neighbors' yards. You can fill in the ditch with perforated pipe and gravel to create a French drain that directs water flow away from your house to a lower point in your yard or a small drainage pond.
Dig the ditch so it is at least 12 inches wide and 12 inches deep to allow enough area for water to collect and drain. Provide a 1/2- to- 1-percent slope in the ditch so water flows downhill; in other words, the ditch should drop 1/2- to- 1-foot in elevation for every 100 feet of ditch length. Extend the ditch, if necessary, so it ends at a location that is downhill from your house. If depositing the water downhill means you would flood your neighbor's yard, you can dig a small retention pond to hold the water while it slowly drains into the soil.
Line the bottom of the ditch with permeable landscaping fabric or geotextile fabric that prevents soil from clogging the pipe but still allows water to seep through into the soil. Never use plastic weed barriers because this disrupts the ability for water to drain into the soil.
Spread 4 inches of clean 1/2- to- 1-inch gravel evenly across the bottom of the ditch. Avoid using crushed rock, especially limestone, which can become hard like cement after getting wet, restricting the flow of water through the ditch.
Place 4-inch plastic perforated pipe, also known as drainage tile, in the bottom of the ditch. Depending on the type of pipe you use, you simply push two ends together to connect two pieces or they attach with a coupling.
Cover the end of the perforated pipe, where the pipe deposits at the base of a hill or in a retention pond, with wire mesh hardware cloth to prevent debris and small animals from entering the pipe.
Cover the drainage tile with permeable landscaping fabric so the tiny perforations don't get clogged with mud. Cut the landscaping fabric about 8 inches wider than the drainage tile to allow several inches of overlap into the gravel.
Fill in the ditch with gravel around the perforated pipe up to the trench edge. Rake the gravel smooth with a bow rake. Mix the gravel with river stones, if desired, to give the filled ditch more of a dry stream appearance. If you would prefer not to leave the gravel exposed, you can fill the ditch to within 4 inches of the edge, then add 4 inches of coarse sand over the gravel and seed the area with grass seed that thrives in sandy soil.
Things You Will Need
- Digging tools
- Measuring tape
- Permeable landscaping fabric or geotextile fabric
- 1/2- to- 1-inch gravel
- 4-inch plastic perforated pipe
- Hardware cloth
- Coarse sand
- Do not allow vehicles, heavy machinery or foot traffic on the French drain because heavy traffic can cause soil compaction under the pipe or crush the perforated pipe.
- If the ditch channels frequent, fast-flowing water that could easily move the gravel in a downpour, you should consider a dry creek bed instead of a French drain. A dry creek bed uses some smaller rocks, about the size of an egg or fist, but also places large and medium rocks in the ditch that don't move as easily with water flow. You can still use the perforated pipe to direct the flow of water, but avoid placing large boulders on the pipe.
- Always contact your local code enforcement or storm water management office before you make any changes to the ditch and drainage systems around your home. In many cases, there are strict guidelines regarding storm water management and drainage systems, so you must make sure it is legal to fill in the ditch and comply with any regulations.
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- Grounds Magazine: How To: Install a French Drain
- Easy Digging: How to Dig and Install a French Drain to Collect and Move Rain Water Away from Your Home
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