How much does a french drain cost in Sonoma County?
An exterior french drain costs $10 to $65 per linear foot in LawnStarter’s published range. That puts a 100 foot drain at $1,000 to $6,500. Bob Vila publishes $10 to $50 per foot, and both guides put the national average at about $5,000.
These are national figures, and California labor and materials run higher. We install french drains and yard drainage across Sonoma County. Each job gets a written estimate after we see the site.
What does a french drain cost per foot?
LawnStarter prices an exterior french drain at $10 to $65 per linear foot, and Bob Vila at $10 to $50. For a whole job, LawnStarter’s typical range runs $1,650 to $12,250. Bob Vila’s typical range is wider, at $500 to $18,000.
The pipe is the cheap part. LawnStarter prices it at $0.50 to $3 per linear foot, and pea gravel at $25 to $53 per ton.
Interior french drains are a separate and pricier category. Bob Vila lists them at $40 to $100 per linear foot. This guide covers exterior drains in yards, along driveways and behind walls.
What does a french drain cost for 50, 100 and 200 feet?
LawnStarter publishes $500 to $3,250 for 50 feet of exterior french drain. It lists $1,000 to $6,500 for 100 feet and $2,000 to $13,000 for 200 feet.
The table adds two columns that multiply published per-foot rates by length. One uses Bob Vila’s $10 to $50 per foot. The other uses LawnStarter’s $25 to $50 per foot for a drain behind a retaining wall.
| Drain length | LawnStarter, exterior, as published | Bob Vila, exterior at $10 to $50 per ft | LawnStarter, behind a retaining wall at $25 to $50 per ft |
|---|---|---|---|
| 50 ft | $500 to $3,250 | $500 to $2,500 | $1,250 to $2,500 |
| 100 ft | $1,000 to $6,500 | $1,000 to $5,000 | $2,500 to $5,000 |
| 200 ft | $2,000 to $13,000 | $2,000 to $10,000 | $5,000 to $10,000 |
Every figure here is a national number. Bob Vila notes that the cost varies from community to community with the going price of labor. Use the table to size the job, then get a local number.
What pushes the price of a french drain up or down?
Length sets the base, since both guides price the work by the foot. Depth comes next. LawnStarter describes a trench 1 to 2 feet deep. Bob Vila puts the minimum at about 18 to 24 inches below the area that needs protection.
Then comes the outlet. The pipe has to carry the water downhill to a safe spot. That can be daylight, where the pipe ends in the open lower on the property.
A long run to that spot adds pipe and digging. A flat lot with no lower spot may need a dry well at the end of the line.
A drain behind a retaining wall has its own published rate. LawnStarter lists it at $25 to $50 per linear foot. On the block and stone retaining walls we build, the drain line goes in with the wall. That gives water a way out from behind the blocks.
How do Sonoma County rain and clay affect a french drain?
Rain here comes in a short, heavy season. NOAA’s 1991 to 2020 normals give the Petaluma Airport station 25.56 inches a year. December, January and February bring 15.19 inches of it, about 59 percent. The Santa Rosa station runs wetter, with a normal of 31.53 inches a year.
Clay soil holds that winter water in place. The USDA describes the Clear Lake series, a clay soil of central California’s coastal valleys, as poorly drained. Its permeability is slow to very slow. During wet winter months, its water table can sit very near the surface.
A yard on soil like that stays wet long after a storm. A french drain gives the water a gravel path into the pipe, and the pipe carries it downhill. July averages 0.01 inches at the Petaluma Airport station, so summer is the easy time to open a trench.
Is a french drain worth it?
For ground that stays soggy after rain, usually yes. LawnStarter says french drains typically last 30 to 40 years. Spread over 30 years, the $5,000 national average comes to about $170 a year. LawnStarter calls french drains an affordable way to prevent flooding and water damage.
A french drain is built for water in the soil. Water running across the surface, like runoff down a driveway, calls for a surface drain or a regrade.
What are the alternatives to a french drain?
The main alternatives are regrading, a catch basin with solid pipe, a channel drain and a dry well. Each fits a different water problem, and the published ranges vary widely. Bob Vila and LawnStarter price three of them, shown below with the exterior french drain for comparison.
| Option | What it handles | Published range |
|---|---|---|
| Regrading | Ground that slopes toward the house | $500 to $3,000 for grading (Bob Vila) |
| Channel drain | Runoff crossing pavement toward a door or garage | $30 to $150 per linear foot (Bob Vila) |
| Dry well | Water with no lower spot to drain to | $500 to $3,000 (LawnStarter) |
| Exterior french drain | Soggy ground that holds water | $10 to $65 per linear foot (LawnStarter) |
Regrading reshapes the ground so water runs away from the house. Bob Vila notes that grading can work in tandem with a french drain in the same yard.
A catch basin is a concrete box set at the low spot where surface water collects. Solid pipe carries the water from the basin to an outlet. The cost depends on the size of the area and how far the water travels. We price it on site.
A channel drain is a narrow grated channel set into the pavement. It fits where a driveway slopes toward a garage and the runoff heads straight for the door. If you are planning a new asphalt driveway, the slope can be set so water runs away from the garage.
A dry well stores the water underground. Bob Vila says it releases the water back into the soil in a controlled manner. It fits a flat lot with nowhere lower to send the water, though slow clay makes that release slower.
Can you install a french drain yourself?
You can, but it is heavy work. LawnStarter puts a do-it-yourself drain at about $700, against about $3,000 to have one installed. It still advises leaving the job to the professionals, because the install is labor-intensive and takes precision.
The precision is in the fall. The pipe has to slope steadily from the wet spot to the outlet, or water sits in the line.
California also has a dig law. Section 4216.2 of the Government Code requires notice at least two working days before digging begins. That notice goes to the regional notification center, which you reach by calling 811.
Do you need a permit for a french drain in Sonoma County?
It depends on the size of the job and where the property sits. In unincorporated Sonoma County, Permit Sonoma requires a grading permit when cut or fill exceeds 50 cubic yards. Cut or fill deeper than 3 feet also triggers one. Inside city limits, the city’s own permit counter sets the rules.
We check which rules apply before we quote. Our guide to permits for paving and grading in Sonoma County covers the county’s other rules.
What does the estimate visit look at?
We look at where the water starts and where it can safely leave, then plan the run between them. Sometimes the answer is a french drain. Sometimes a catch basin or a regrade fits the site better. Then you get a written estimate.
Rich’s Paving is a third generation family paving company. We have paved Sonoma County since 1988. When you want a number for your yard, give us a call and ask for an estimate.