Downspout drain pipe
Roof water is one of the biggest loads your foundation sees. A buried pipe can move it, if the outlet is right.
A downspout drain pipe is a solid pipe, usually buried, that takes roof water from the bottom of a downspout and delivers it well away from the house. Done right, it removes the single largest source of water beside many foundations. Done wrong, it clogs, freezes or simply drops the same water in another bad spot.
This page prints no prices. Costs vary by region and year. It covers how the pipe should behave. The gutter and roof side belongs to a sister site, so this page stays on the ground.
Why buried pipe beats a splash block
A short splash block lets water pool a couple of feet from the wall, where soil often slopes back toward the house. A solid pipe carries the water the whole way to a safe outlet. For the reasoning behind distance and slope, read grading and downspouts.
Use solid pipe, not perforated
A buried downspout line should be solid, not perforated. Perforated pipe leaks water out along its length, which defeats the purpose. Roof water should travel in a closed pipe and only leave at the end. Perforated pipe is for collecting groundwater, as in drain tile, and the two should never be tied together.
What the pipe needs to work
- A steady downhill fall along the whole run, with no low spots where water sits.
- A connection at the downspout that is tight enough to carry heavy rain without spilling.
- An outlet that lets water leave: daylight on a slope, a pop-up emitter in the yard or a suitable storage structure.
- A way to clear debris, such as a cleanout or a removable cap at the top.
Leaves, shingle grit and small debris wash down with every storm. A line with no way to reach it will eventually stop, and you will find out when the downspout backs up during a storm.
Where the water should end up
The outlet is the part people skip. Water that exits two feet from the wall is barely better than a splash block. Aim for a spot well clear of the foundation, on ground that slopes away, and not onto a neighbor's property or a walkway. Rules on where you may discharge roof water differ by town, so ask your building department.
If the soil is tight clay, burying the water in a stone pit may not work, since there is nowhere for it to soak in. Read dry wells before you rely on one.
Cold-climate problems
In freezing weather, water left in a buried line can freeze and block it. A line with a steady fall drains itself between storms, which is another reason slope matters. A pipe that holds water in a belly is the one that cracks or plugs.
Keep it separate from other drains
Do not connect a downspout line to your foundation drain, your sump discharge or a sewer pipe. Roof water in volume can overwhelm those systems and send water where you do not want it. Check the sump pump guide for how a sump should discharge on its own.
Know when this is not the problem
If the downspouts are already far from the house and the basement still gets wet, the water is coming from somewhere else. The water diagnosis tool helps narrow down the source. If a wall leans or cracks, that is a question for a licensed structural engineer, not a drainage job, and you should not dig beside it.
Take a position: a long extension on top of the ground is a fair first move. And a buried pipe is worth it when the extension is in the way or the yard is too flat for it to drain.
Frequently asked questions
What is a downspout drain pipe?
A solid pipe, usually buried, that carries roof water from the bottom of a downspout to an outlet well away from the house.
Should a downspout pipe be perforated?
No. Perforated pipe leaks along its length. Use solid pipe for roof water so it only exits at the outlet.
How far should a downspout drain from the house?
As far as the site allows, well past the area where the ground slopes back toward the wall. Local rules may set limits, so check with your building department.
Can I connect a downspout to my foundation drain or sump?
It is best not to. Roof water in volume can overwhelm those systems. Keep downspout lines separate.
Why does a buried downspout line clog?
Leaves, shingle grit and debris wash in with every storm. A cleanout or removable cap lets you clear it.
Sources
What this page explains is based on these official sources. If you check one and it does not match what you read here, send it to us and the article gets corrected.
- US EPA. What You Can Do to Soak Up the Rain
- US EPA. Soak Up the Rain. Managing stormwater around a property