French Drain Installation
in Houston, TX

Do French drains work in Houston clay, and where should they not go?

Yes, when they work as collectors with fall and a real outlet. Houston clay drinks water fast when it is cracked and dry, then swells shut and barely lets water through. So the drain has to carry the water out by gravity, and it will not soak away. It is the wrong tool for a flat yard with nowhere to send the water. It is also wrong for a buried soak pit or for heavy sheet flow off a neighbor's higher lot. In those cases a swale, a regrade or a catch basin is the better answer. See our yard drainage page for the surface options.

How much does a French drain cost in Houston?

There is no flat rate, because the cost tracks the yard. The price depends on a handful of things.

• Run length and trench depth.
• Number of laterals.
• Outlet type: a curb core, a ditch tie-in or a pop-up emitter.
• How tight the access is, and any sprinkler repair.
• Sod or rock at the finish, and any permit work.

How deep and how much slope does a French drain need?

Depth is set by the wet spot and the outlet elevation, and yard runs often land somewhere around 12 to 24 inches deep. Slope matters more than depth. The pipe needs steady fall of at least 1/8 inch per foot, which is about an inch every 8 feet. We check that fall with a laser before backfill. At the house, code wants the ground to drop 6 inches in the first 10 feet. Where the lot cannot give that, a drain or a swale has to do the job.

Where does the water go: curb, ditch, pop-up emitter or the sewer?

It goes to an outlet the City or county allows, never onto the neighbor. On a curb-and-gutter street in Houston, the run ties to a 4-inch Schedule 40 PVC pipe through the curb. On an open-ditch street, the pipe meets the ditch square, below the driveway culvert, with a headwall to stop erosion. A pop-up emitter works only where it sits lower than the inlet with steady fall the whole way. We never tie a drain into the sanitary sewer line. Texas Water Code 11.086 also bars pushing your runoff onto a neighbor. For open-ditch and acreage lots, see our culverts page.

Do I need a permit for a French drain in Houston?

Inside the City of Houston, tying area drains, catch basins or downspouts into a drain line takes a plumbing permit pulled by a City-registered master plumber. Drainage plans the City reviews also have to show an approved outfall, not sheet flow onto the street or the neighbor. Harris County and the suburbs each have their own rules, and an HOA may need to approve a curb outlet or an emitter. We check with your city or county before we dig, so the outlet is settled before the trench is cut.

How long does a French drain last, and what if mine is clogged?

A French drain lasts when the fabric keeps the clay out, the pipe has fall, and the outlet stays open. Most failures come from no fabric, no fall, a crushed or buried outlet, or tree roots. We flush the run through cleanouts or rebuild it with new fabric and clean rock. If the real problem is a yard that never had the fall to drain, a regrade is the honest fix. Call (832) 576-3278 and we will shoot it and tell you.