Guide
The pipe is the easy part. The place the water leaves your lot decides whether a French drain works, what it costs and whether a city has a say in it.
Updated November 5, 2026
A French drain drains to an outlet lower than the trench: usually a curb core through the street curb, the alley line, a grassed swale, a pop-up emitter in a lower part of the lawn, or a sump pump where nothing lower exists. It cannot drain onto a neighbor’s lot. Rein Irving Drainage Company settles the outlet before drawing the trench, because the outlet decides the rest.
A French drain collects water from the soil and moves it downhill through a perforated pipe. If the end of that pipe is not lower than the start, water sits in the stone and the drain becomes a buried bathtub. Two outlet faults sink a lot of French drains: no outlet at all, or an outlet set too high. Choosing the outlet first also sets the depth, the length of solid pipe and much of the price.
A curb core is a hole cored through the street curb, with a solid pipe ending flush in the gutter. It is the most common outlet on front-draining lots and the one that most often needs city approval, because it is work in the public right-of-way. The pipe usually runs under the parkway and sometimes the sidewalk, which adds digging and restoration.
Where a lot backs onto an alley, the alley is often the nearest low point. University Park, for example, requires roof drainage to be piped through the curb or to the alley line. An alley outlet can be much shorter than a run to the front curb.
A swale is a shallow grassed channel that carries water along a property line to the front or back. The French drain empties into the head of the swale and the swale carries the water away on the surface. It needs steady fall; Grand Prairie, for instance, sets a minimum of 1 percent slope for earthen drainage. Shaping one is a yard grading job.
A pop-up emitter is a small lid at the end of a solid pipe. Water pressure lifts the lid and the water spreads across the lawn, then the lid drops shut. It only works where the lawn keeps falling away from the house past the emitter, and where the released water will not run straight back or onto a neighbor.
On a flat lot or one lower than the street, gravity has nowhere to send the water. A sump collects it and a pump lifts it to a curb, alley or swale. It adds a moving part and needs power, so it comes after the gravity options have been ruled out.
| Outlet | Where it fits | Typical limits | Approval |
|---|---|---|---|
| Curb core | Lot falls toward the street | Long runs on deep lots; crosses the parkway | Often a city permit; Coppell issues it as an engineering permit |
| Alley line | Lot backs onto an alley that sits lower | Alley grade must be lower than the trench | Varies by city |
| Swale | Room along a property line for a shallow channel | Needs steady fall and must not concentrate water on a neighbor | Grading rules may apply |
| Pop-up emitter | Lawn keeps falling away past the emitter | Fails on flat lots; water must not reach a neighbor | Usually none on your own lot |
| Sump and pump | No lower gravity outlet | Power, upkeep, still needs a discharge point | Depends on the discharge point |
Rules for where yard water may go are local, and the details matter.
For a city-by-city view, see drainage permits in Irving and Dallas and the pages for Coppell, Grand Prairie and University Park.
Pointing the pipe at a lower neighbor is the cheapest outlet on paper, and it is not available. Texas Water Code section 11.086 makes it unlawful to divert or impound the natural flow of surface water in a way that damages another property. A French drain gathers water from a strip of yard and releases it at one point, which is exactly the kind of concentration that causes the damage. Grand Prairie spells this out in its own code. The neighbor runoff in Texas guide covers the other side of the fence, when the water is arriving at your lot.
A dry well or gravel pit at the end of the pipe looks like an outlet but is really a storage tank that empties by soaking into the soil. In the Ferris and Heiden clay mapped at the Las Colinas soil sample point, water soaks in extremely slowly, so the pit fills in the first storm and stays full. On sand over clay, the water stops on the clay just as it did before the drain was built. The dry wells in clay guide explains the rare cases where one helps.
Start by finding the lowest point you could legally reach: the curb, the alley or the back of a sloping lot. Measure how far it is and roughly how much lower it sits than the wet area. If it is close and clearly lower, a gravity outlet is likely. If it is far, barely lower or higher, expect a deeper trench or a pump. Outlet choice moves cost more than footage does, which the French drain cost guide shows with examples. To have the outlet worked out for your lot, send a photo and your address.
Only if the ground keeps falling away from the end of the pipe and the water can spread out without reaching a house or a neighbor's lot. On most flat Irving lots it cannot, so the pipe needs a curb, alley, swale or pump outlet instead.
Yes, as long as the shared solid pipe is sized for both and each line keeps steady fall to the junction. Sharing one curb core or swale is often cheaper than building two separate outlets.
The DFW area averages about 29 freezing days a year, usually short spells. An emitter with fall on its feed line drains back after each storm, so little water sits in it to freeze. A line laid flat that holds water is the one that gives trouble.
Send your address and a photo of the wet area; the outlet is the first thing we work out.
