If you’re in the U. S. , call the 811 “Call before you dig” hotline, which will connect you to your local call center. An agent will come to your site within a few days to flag any underground hazards like municipal pipes or cables. Also be sure to plan your drainage route so it runs at least 1 m (3. 3 ft) from any walls or fencing, and try to avoid any posts, shrubs or tree roots.

Also establish whether or not your French drain would cause hardship for neighbors in terms of groundwater runoff. Running excess water onto someone else’s land could lead to a potential lawsuit. Ideally the French drain runs off in a relatively unused section of land, away from any buildings, into sandy soil which allows water to pass through easily.

Sink a couple of stakes on far ends of the line and connect them with a string. Use a leveling tool to measure the grade of the string and slope—ideally, it’ll have a downhill grade of at least 1%, or a drop of 0. 125 in (0. 32 cm) per 1 ft (0. 30 m). Never plan your French drain to drain into a neighboring property; it’s almost always illegal, and can pose numerous zoning issues and dangers, regardless. Optionally, hire a surveyor or other professional to help pin down the right dimensions and placement for your drain.

Periodically check the depth of the trench as you dig to ensure it consistently slopes downwards. The ditch depth and grade doesn’t have to be perfect, but ensure that there are no “bellies” in your drainage, or areas in which water can pool and be held. You might also rent a trencher from a hardware store, which is a specialized tool for digging trenches, or use a backhoe, but we recommend using a simple spade, since it’s the most precise and controllable tool.

Place a cap on the upper end of the pipe to prevent any soil or gravel from entering the pipe and clogging it downstream. [7] X Research source Alternatively, begin the length of pipe with a downspout catch to more effectively drain water from a targeted area.

The bottom end of the pipe will remain below ground, but alternatively, install a drain emitter for easy, above-ground access. Simply attach the emitter to the end of the pipe, and bury it so that its top surface is level with the ground.

With this setup, the water forks off into the T-branch and is dispersed over a wider area, preventing pooling at the bottom of the French drain.