How Much Does a French Drain Cost in Oregon?

A French drain in the Portland area runs about $30 to $70 per linear foot. That range comes from a 2026 price guide published by a Portland drainage company. The same guide puts a typical backyard drain at $1,500 to $5,000.

National cost guides quote about $10 to $90 per foot for most outdoor drains. The type and depth set where a job lands in that range. These are market numbers, not our price list. Around Tualatin, clay soil and the distance to an outlet can push the price up.

Green Tree Landscape and Maintenance builds French drains and yard drainage in yards around Tualatin. We work on the south and west side of the Portland metro.

What does a French drain cost per foot in Oregon?

Published market ranges, not our price list:

At the Portland rate, a 50-foot run across a backyard works out to $1,500 to $3,500. A 100-foot run works out to $3,000 to $7,000.

Headline national averages of $5,000 or more often include drains inside basements. That work belongs to another trade, and national guides price it at $40 to $100 per foot.

What drives the price of a French drain?

Most of the price is labor. National guides put the perforated pipe itself at about $0.50 to $3 a foot.

• Length. Every foot of trench takes digging, washed rock, filter fabric and pipe.
• Depth. A shallow curtain drain catches water near the surface. A deeper drain reaches water held in the soil, and it takes more digging and more rock.
• The outlet. The pipe has to fall at least 1 percent, about an inch every 8 feet. A far-off outlet means a longer run.
• Clay. A Portland price guide calls local clay dense and hard to dig, which adds labor time.
• Access. A mini excavator needs a gate wide enough to reach the backyard. Where it cannot fit, the trench gets dug by hand.
• Buried lines. Oregon law requires notice to Oregon 811 at least two business days before digging. The utilities mark their own lines. Private sprinkler and drain lines stay unmarked, and digging around them takes extra time.
• Add-ons. A catch basin or a downspout drain line is priced on top of the drain.
• Putting the yard back. A trench leaves a strip of torn-up lawn. New sod over the trench runs about $0.85 to $1.75 per square foot in national guides.

Why do so many Tualatin Valley yards stay wet all winter?

NOAA’s 1991 to 2020 normals put Portland at about 37 inches of rain a year. Close to 9 of every 10 inches fall in the wet season, October through May.

The soil holds that water near the surface. USDA soil surveys describe much of the Tualatin Valley floor as silt loam laid down by the Missoula Floods. Aloha silt loam, the most widespread soil under Beaverton and Tigard, is rated somewhat poorly drained. In normal years, water perches in it 12 to 24 inches down.

Many Tualatin yards sit on well-drained terrace loam. About an eighth of the city is Quatama loam, with water 16 to 30 inches down from January through March. Along the Tualatin River, Wapato soils can flood from December to April.

Dayton soils, common across the Willamette Valley, have a clay subsoil. Water perches on it from November to April. On Happy Valley and southwest Portland slopes, Cascade silt loam holds winter water on a hardpan about 2 feet down.

Most French drains sit 1 to 2 feet below grade, national guides say. That depth reaches the water perched in these soils. On a flat valley lot, the hard part is finding enough fall to an outlet. That can mean a longer run.

Is a French drain the right fix, or is something else?

A French drain fits water that soaks into the lawn and stays there. The grass squishes underfoot for days after a storm, and by March the lawn is more moss than grass. OSU Extension lists drain tile and catch basins among the fixes for wet, mossy lawns.

Other problems call for a different piece:

• A catch basin is a box with a grate, set in a low spot where rain puddles. Solid pipe carries the water away.
• A channel drain is the long, narrow version, set along the edge of a patio or a walkway.
• A downspout drain line carries roof water away from the house in solid pipe.
• Regrading reshapes the soil so the ground falls away from the foundation.
• A dry well is a buried pit that lets water soak into the ground. It only works where the soil drains and the groundwater sits deep.

When a whole yard is being redone, drainage goes in before the new beds and lawn. That work fits inside a full landscape makeover.

A new retaining wall needs its own drain behind it. National guides price that drain at $25 to $50 per foot. Our guide to retaining wall costs in Oregon covers the wall itself.

Where can the water go under Oregon stormwater rules?

Every French drain needs an outlet lower than the wet spot. The simplest outlet is daylight, where the pipe ends at a low point on your own lot. A tie-in to a public storm line needs approval first.

The rules change by city and agency:

• Portland: a dry well needs at least 5 feet between its bottom and seasonal groundwater. Under that rule, a lot with winter water 2 feet down has no room for one. Downspout outlets stay at least 5 feet from a neighbor’s property line.
• Washington County: Clean Water Services, the stormwater and sewer agency for urban Washington County, reviews new or changed storm lines. It also reviews grading or digging that disturbs more than 500 square feet.
• Clackamas County: in its district, Water Environment Services holds dry wells to Oregon DEQ’s underground injection rules.

The permit question is settled before work starts. Portland’s Clean River Rewards program can cut a home’s stormwater fee by up to 35 percent. It applies when rain soaks into the ground on the lot. Dry wells and French drains are on its list, and a permit may be required.

How do you get a real number for your yard?

A real number depends on where the water sits and how far the pipe has to run. Photos from the last big rain help, since they show where the water collects.

We look at the yard and put the quote in writing. Read how we build a French drain, then call or text (971) 772-9892.