Buried downspout drain
A pipe under the lawn can take roof water well clear of the foundation. It only works if the water has somewhere to end up.
A buried downspout drain is a solid pipe that takes water from the downspout, runs it underground and releases it away from the house. Done well, it removes the biggest single load of water from the foundation. Done badly, it hides the problem.
This page prints no prices. It explains how the system works, so you can judge a plan before anyone digs.
What the pipe actually does
A downspout collects water from a large roof and drops it in one spot. Without a way out, that spot is right beside the wall. A buried line picks the water up at the base of the downspout and carries it across the yard on a steady downhill run.
The pipe is solid, not perforated. Its job is to move water, not to leak it into the soil. The downspout drain pipe page covers the pipe itself in more detail.
Where the water ends up
This is the question that decides everything. The pipe needs a safe exit.
- Open daylight at a lower part of the yard, with a splash area so the soil does not wash out.
- A dry well or other spot that can take the flow, if local rules allow it.
- A storm drain connection, only where your town permits it.
A line that ends in a closed hole in the lawn fills up and backs up to the gutter. If you are weighing a dry well, read dry wells first.
The mistakes that make it fail
The first is too little slope. Water must keep moving downhill, or silt settles and the pipe clogs. The second is joints that are not sealed, which lets roof water leak out right beside the foundation. The third is no clean-out, so a blockage means digging up the yard.
Leaves and grit from the roof are the usual cause of clogs. Gutter guards and a screened inlet help, but nothing replaces a look after storms.
Do the easy part first
Before you bury anything, check whether a surface extension would do the job. A downspout that discharges well clear of the wall onto ground that slopes away is easier to fix and easy to inspect. The grading and downspouts page covers that first step. Take a position: bury the line only when the yard layout makes a surface extension impractical.
Where to stop and call someone
Do not trench beside a foundation wall that is cracked, bowed or leaning. Digging next to a stressed wall can make it worse. A licensed structural engineer can assess it, and an independent one has no repair to sell you. Local rules decide where you may discharge roof water. Ask your building department before you connect or redirect anything.
Frequently asked questions
What is a buried downspout drain?
A solid pipe that takes water from a downspout, carries it underground and releases it away from the house.
Should a buried downspout pipe be perforated?
No. The line is meant to move water, not leak it into the soil beside the foundation. Use solid pipe with sealed joints.
Where should a buried downspout drain end?
At a safe exit, such as open daylight on lower ground. A closed end fills up and backs water into the gutter.
Why does a buried downspout drain clog?
Usually leaves and grit from the roof, or a pipe with too little slope so silt settles.
Can I connect it to the storm sewer?
Only if your town allows it. Rules on roof water are local, so ask your building department.
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