Curtain drain
A curtain drain catches water moving through the soil and carries it around the house. It suits some yards and does nothing for others.
A curtain drain is a trench filled with gravel, usually with a perforated pipe in the bottom, that intercepts water moving through the soil and sends it somewhere else. It sits uphill of the area you want to keep dry. Water flowing downslope drops into the trench instead of continuing toward your foundation.
This page prints no prices. Costs vary by region and site, and it explains the idea so you can judge a proposal.
How a curtain drain works
The trench cuts across the path of shallow groundwater. Gravel gives that water an easy route, and the pipe carries it along the trench to an outlet. The outlet matters as much as the trench. It has to drain somewhere lower, such as a daylight exit on a slope or a storm system where local rules allow it.
Think of it as a ditch you cannot see. It does not pull water out of the ground like a pump. It only catches what arrives.
Where a curtain drain makes sense
- A sloping yard where water seeps downhill toward the house.
- A wet strip that appears at the same spot after every storm.
- A property with a natural low exit on one side.
- Soil that drains slowly and holds shallow water above a clay layer.
On a flat lot with no outlet, a curtain drain has nowhere to send what it catches. It fills up and stops working.
Curtain drain or French drain?
The names overlap, and people use them loosely. A curtain drain works on the yard, intercepting water uphill of the house. A footing or perimeter drain sits at the base of the foundation. The French drain vs drain tile page sorts out the terms, and French drain without pipe covers the gravel-only version.
The mistakes that make it fail
The first is skipping the outlet. A trench with no exit is a long, narrow pond. The second is placing it on the wrong side, downhill of the problem. The third is using soil instead of clean gravel, which clogs the trench within a few seasons.
Fabric around the gravel helps keep fine soil out. Without it, silt works into the stone and the drain slowly closes.
Fix the easy water first
Before anyone digs a trench, check the simpler sources. Downspouts that dump at the wall and soil that slopes toward the house put more water beside a foundation than most groundwater does. The grading and downspouts page covers both. Take a position: a curtain drain is worth considering only after those are right and the yard still stays wet.
If water pools on the surface for days, read standing water in the yard too. Not every wet yard needs a buried drain.
Where to stop and call someone
Do not dig a trench close to a foundation wall that is cracked, bowed or leaning. Digging beside a stressed wall can make it worse. That is a question for a licensed structural engineer, and an independent one has no repair to sell you. For rules on where you may discharge water and how deep you may dig, ask your building department, because requirements are set locally.
Frequently asked questions
What is a curtain drain?
A gravel-filled trench, usually with a perforated pipe, that intercepts groundwater uphill of a house and carries it to an outlet.
Is a curtain drain the same as a French drain?
The terms overlap. A curtain drain intercepts water in the yard, while a footing drain sits at the foundation base.
Where does a curtain drain need to empty?
Somewhere lower than the trench, such as a daylight exit on a slope. Local rules may limit where you can discharge.
Will a curtain drain fix a wet basement?
Only if the water comes from shallow groundwater moving toward the house. Roof water and bad grading are usually bigger causes.
Can I dig a curtain drain next to my foundation?
Not if the wall is cracked or leaning. Digging beside a stressed foundation can make it worse, so ask a licensed structural engineer first.
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