What is an Underground Downspout?

An underground downspout is a pipe that connects to the gutters that drain water off of the roof of a house. This type of downspout is usually buried underground, and drains water away from the foundation of the home. Drained water may lead to an open pipe located a safe distance away from the home, or to a collection unit located in an area of the yard that benefits from gradually released water. This type of downspout is typically installed by professional contractors, but may also be installed by the homeowner.

Traditional downspouts connect to the gutters around the edge of a home, and end above ground, a few inches from the home. These generally allow water to drain from the roof and collect directly beside the foundation. This water, however, may seep beneath the foundation and flood the crawl space or basement. Therefore, an underground downspout can be used to eliminate such flooding. This can be especially useful for homes that have grounds graded in such a way that water tends to collect there.

Prior to installation of an underground downspout, some light maintenance must be done to the home. Any low areas of land directly around its foundation should be back-filled to create the best drainage possible for the downspout. This will naturally divert water from the home that may not be caught by the gutters.

The underground downspout typically carries water away from the home, into a receiving container that allows overflow to filter out onto the property, at a safe distance. These usually also contain slots to allow standing water to drain back into the ground. They should be located at least eight feet (2.43 m) away from the building. Some underground downspouts end in an open pipe that protrudes from the side of a hill or from the curb in the street in front of a home.

These spouts may be installed professionally or by the homeowner. Many companies offer underground downspout installation kits on the Internet, and these generally include step-by-step installation instructions. This type of project commonly involves digging a ditch, into which the new downspout is placed.

Piping for this type of downspout should usually be placed just below the surface of the lawn. Non-perforated PVC piping with a smooth interior surface is the most common type used to create an underground downspout. This is more easily cleaned by drain-cleaning solutions than the that used in above-ground downspouts. It also prevents tree roots from penetrating it and creating clogs.

When installing one, angle the underground downspout downwards gradually as the land extends away from the home. This natural plane should allow the water to run away from the building, towards the open drain or collection area. Such grading can also prevent water from backing up or standing in the pipes.