- Regrading fixes ground that slopes the wrong way. It's often the first step.
- Swales move large volumes of surface water across the yard.
- French drains handle water moving through the soil, not big surface flows.
- Many properties need a combination, planned as one system.
"I need a French drain" is one of the most common things we hear on drainage calls. Sometimes that's exactly right. Often it isn't. A French drain is a great tool for one specific job, and it gets installed for problems it can't solve. Before choosing a fix, it helps to understand what each one does.
Regrading: changing the shape of the ground
Regrading reshapes the soil so water flows where you want it. The most important area is right around the house: ground should fall away from the foundation. A common building code standard is about six inches of fall within the first ten feet. Over time, backfill around foundations settles, and a yard that once sloped away can end up sloping toward the house.
Best for: negative grade near the foundation, small low spots, and yards where water simply has no downhill path.
Limitations: you need somewhere for the water to go. On flat lots or tight lot lines, grading alone may not be enough.
Swales: shallow channels for surface water
A swale is a broad, shallow channel shaped into the yard to collect and carry surface runoff. Done well, it's barely noticeable: a gentle dip you can mow across. Swales can be grassed, or lined with rock where flow is heavier or the slope is steeper.
Best for: water flowing across the yard from uphill neighbors, driveways, or your own upper lot; directing runoff around a house or patio.
Limitations: needs enough fall to keep water moving and a safe outlet at the low end. On clay, a swale without enough slope can become a long puddle.
French drains: intercepting water in the soil
A French drain is a trench with perforated pipe surrounded by washed stone, wrapped in filter fabric. Water in the surrounding soil seeps into the stone, enters the pipe, and flows to an outlet. It's designed for groundwater and slow seepage, the kind of water that keeps a hillside spongy or seeps toward a basement wall.
Best for: wet areas caused by water moving through the soil, seepage at the base of a slope, and areas behind retaining walls.
Limitations: a French drain can't absorb a fast surface flow from a summer downpour. Water sheets right over it. When surface water is the issue, a French drain needs surface inlets added, or a different solution.
How French drains fail
The most common failure we see is clogging. In clay soil, fine particles migrate into the stone and pipe. Without filter fabric, or with the wrong stone, a drain can lose much of its effectiveness within a few years. Insufficient slope and a buried, blocked outlet are the other usual suspects.
Quick comparison
| Problem | Usually solved by |
|---|---|
| Ground slopes toward the house | Regrading |
| Sheet flow from uphill or a driveway | Swale, sometimes with a channel drain |
| Spongy ground that stays wet between rains | French drain |
| Puddle in a flat low spot | Catch basin piped to an outlet, or regrading |
| Roof water dumping at the foundation | Downspout drain lines |
| Erosion channel down a slope | Rock-lined swale or dry creek bed |
Where the water ends up
Every drainage system needs a safe outlet: a lower part of your property, a ditch, a rain garden, or a storm system where allowed. Water generally can't be redirected onto a neighbor's property in a way that causes harm. Planning the outlet is as important as planning the drain.
Combining solutions
Most of our drainage jobs use two or three of these together. A typical example: regrade along the back of the house, tie the downspouts into solid underground pipe, and run a swale to carry yard runoff past the patio to a dry creek bed. Each piece handles a different source of water. If you're not sure where your water is coming from, start with our guide to diagnosing a soggy yard, and check your downspouts first. They're the cheapest fix there is.