How to Install Downspout Drain Pipes

Downspouts play a very important role a well-functioning gutter system. Conversely, downspout drain pipes channel water in the gutter to the downspout ditch or drain, commonly called the French drain. Here, we will discuss about installing downspout drain pipes.

Downspout Drain Pipe Types

There are two types of downspout drain pipes, the thin-walled plastic pipe and the black corrugated pipe. However, these two are not recommended by most plumbers. Instead, their advice is for homeowners to use PVC pipes, the type of piping used in indoor plumbing.


Step 1: Dig a Trench.
If this will be a new drain line installation, it is important to start with the French drain. This is a trench that needs to be dug at a minimum of 8 feet away from the foundation of your house and should have a perforated pipe and surrounded by gravel or sand to channel water flow away from your home. Moreover, it is important to have a filter fabric containing rocks of different sizes, from ½” to 12”, on the trench, the larger rocks placed at the bottom.

Step 2: Excavate Soil For The Pipe.
Since the downspout needs to be buried under the ground, you also need to excavate the soil to give room to the pipe. The grading of the soil as well as the slope is also important and should be noted.

Step 3: Install The Downspout Drain Pipe.
Downspout pipes can have a size of either 2” x 3” or 3” x 4” inches to ensure the smooth flow of water from the gutter down to the drain. A sewer pipe with plastic material can also be used since it is similar to the thick-walled piping used for interior vent or drain piping. This can either be welded or be joined using rubber fittings with gasket.

Connect the pipe from the gutter, usually at one end of the roof, near the foundation of the house and let it go down to the ground and towards the downspout drain. Depending on how long you want to extend the downspout, the angle on which the pipe is placed on the ground down to the French drain should be carefully observed.

From the ground going to the drain, the pipe will be buried underground. As the pipe goes farther towards the drain, it should be buried deeper as well. The ideal drop should be at least 1/8 inch for every foot that the pipe extends.

Note: As for the reason behind keeping the pipe at a certain distance from the foundation, it is because the dirt and soil erodes as time passes by and can easily damage the pipe. To ensure this does not happen, the pipe can pass over the foundation fill at an angle of 90 degrees. It is also important that this is checked to ensure the pipe is draining properly.

Step 4: Cover The Pipe.
Once the downspout is already in place, you can now cover the downspout drain pipe with soil.

Tip: When installing bends for underground piping, it is important to remember to apply a 45 degree angle or smaller fittings to make it easier to fix or troubleshoot if blockage or clogging happens.

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