French drain vs trench drain: what is the difference?

One goes inside your basement. The other goes out in your yard. They fix different problems, so it helps to know which one you have before anybody quotes you.

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Trench drain covered in stone, running away from the house to the far side of a driveway

The difference is where the water is. A French drain, the way we build it, goes inside the basement: we saw-cut the floor next to the wall and lay drain track in the corner where wall and floor meet, and it always runs to the sump pump. A trench drain goes outside: a hand-dug trench that carries water through the yard, finished with river rock level with the grass or tucked under a stepping-stone path.

People use these two names loosely, and other companies may mean something different by French drain. When we say it, we mean the basement drain. When the water is out in the yard, we are talking about a trench drain.

Getting the name right matters because the two jobs happen in different places. One means opening up part of your basement floor. The other means a trench through the lawn, along a bed, or under a path. If you call asking for one and actually need the other, we would rather sort that out on the phone than on the day of the job.

Side by side

How the two drains compare

How we use the two names. Which one your house needs is settled on the free visit.
	French drain	Trench drain
Where it goes	Inside the basement, along the wall	Outside, through the yard
What it deals with	Water coming in at the bottom of the basement walls	A yard that holds water and stays soggy
How we build it	Saw-cut a strip of floor next to the wall, hand-dig the edge, lay drain track in the corner	Dig a trench by hand from where the water collects to where it can leave the yard
Where the water ends up	Always at the sump pump	Away from the house, like the far side of a driveway or an existing concrete drain
Where you find it	Where the basement wall meets the floor	Across the yard, along a bed, or hidden under a stepping-stone path
Dug by hand	Yes	Yes, no machines in the yard

Which one you need

Start with where you see the water

Water in the basement

If you find water where the basement walls meet the floor after it rains, that is where a French drain does its work. It catches the water at the edge of the floor and carries it to the sump pump.

Before we cut into a floor, though, Anthony looks at the outside of the house. He often suggests a foundation swale first, so the water gets led away before it can get to the foundation and overwhelm it. Here is why a swale often comes before a French drain.

Water in the yard

If the ground stays soggy for days, water sits in the same low spot every time it rains, or it collects along a patio or driveway edge, that is a trench drain job. The trench gives the water a way out, and the river rock on top either becomes part of the yard or disappears under a path.

Water in both places

Some houses have both problems. We look at the yard, the outside of the house and the basement on the same visit, and tell you which fix goes where.

What the two have in common

Both get dug by hand. Both also depend on fall. Every drain we build begins at its highest end and drops 1/8 inch per foot of length, which keeps water moving along it instead of sitting.

Recent work