What installation involves
Before installation, the property needs a workable route and outlet. A typical project starts by identifying the water source, tracing a possible route with enough fall, and checking access, utilities, hardscape, landscaping and other conditions that can affect excavation.
- Identify the water source and problem area
- Determine a workable route and outlet
- Review access, utilities and obstacles that affect excavation
- Install the agreed drainage system
- Confirm the discharge path and restoration requirements
Once the route and drainage approach are agreed on, the system can be installed and connected to an appropriate discharge point. The exact excavation, restoration and finishing work depends on the property and the agreed scope.
What affects French drain installation cost?
French drain installation cost depends on the work required at the property rather than a single standard price. Route length and depth, excavation access, obstacles, outlet work, landscape restoration and whether other drainage work is needed can all affect the scope.
- Length and depth of the proposed drain
- Access for excavation and material removal
- Walks, roots, fences, utilities or other obstacles along the route
- Distance and work required to reach a suitable outlet
- Landscape or surface restoration after excavation
- Whether grading, surface drainage or downspout work is also needed
For an estimate request, photos of the wet area after rain, where the water appears to come from, how long the ground stays wet, and anything known about a possible outlet can help start the conversation.
Signs a French drain may help
These are the kinds of problems homeowners usually notice when water is sitting in the soil rather than running off the surface and leaving. A yard that stays wet for days after the puddle is gone, or a soggy lawn that never firms up, is the usual picture.
- The lawn stays spongy days after rain
- The same low area turns to mud every wet spell
- Water seems to rise out of the ground instead of running across it
- A side yard or backyard never fully dries
- Shoes sink in even when it has not rained that day
How an exterior French drain works
A trench is dug along the path where water needs to travel. Drainage stone goes in the trench. A perforated pipe sits in that stone so water can enter through the holes.
Geotextile fabric is often used to keep surrounding soil from mixing into the stone over time. The stone gives water an easy path. The pipe gives it a route downhill.
The outlet is as important as the trench. Collected water has to leave somewhere that will not create a new wet spot — on the same property or toward a neighbor. If the discharge point is wrong, the drain cannot do its job.
This is an exterior yard system. It is meant to collect and move groundwater in the landscape.
When installation is the appropriate work
Installation is the next step when water is in the soil — saturated turf, a strip that stays wet, groundwater that keeps reappearing — and that water has a realistic place to discharge.
Check roof runoff and surface drainage before deciding where a French drain belongs. If a French drain is already in the yard and it stopped working, start with French drain repair instead of a second trench.
Many properties combine methods so the trench collects groundwater rather than fighting a bowl or a splash block. The site visit is where that sequence is set.
What to look at before installing one
These are the conditions worth noting before a layout is chosen.
- Where water first appears after rain
- Where it collects and how long it stays
- The slope of the yard and any low bowls
- How downspouts currently discharge
- Whether an existing drain, swale, or catch basin is already in the mix
- A realistic, safe place for water to outlet
Related drainage solutions
A French drain is one tool. Wet yards often need more than one, or a different one entirely.