The short answer: most residential french drains in the Knoxville area cost between $1,500 and $5,000 installed, which typically works out to $25–$60 per linear foot for an exterior drain. Simple, shallow, short runs can come in under $1,500. Long curtain drains on steep lots, deep footing drains, or interior basement systems can run $6,000–$10,000 or more.
Anyone who gives you a tighter number without seeing the yard is guessing. Here's what actually sets the price, so you can read your quotes intelligently.
Typical Knoxville price ranges by project type
- Buried downspout extension to a pop-up emitter — a few hundred dollars per downspout; the cheapest real fix in drainage.
- Short surface french drain (30–50 ft, shallow) — roughly $1,000–$2,500.
- Standard yard french drain (50–100 ft) — roughly $1,500–$5,000; the most common project we quote.
- Curtain drain protecting a house on a hillside lot — roughly $3,000–$7,000 depending on depth and length.
- Exterior footing drain at foundation depth — $5,000–$15,000; excavation depth is the driver.
- Interior basement or crawl-space perimeter system with sump — roughly $4,000–$12,000.
These are typical ranges, not promises — every yard prices differently, which is exactly why our estimates are free and our quotes are fixed.
The six things that move the number
1. Length. The obvious one — drains are priced largely by the foot.
2. Depth. A shallow curtain drain intercepting surface water is a different job from a drain at footing depth relieving pressure on a basement wall. Deeper trench means more digging, more gravel, and more spoil to haul.
3. Equipment access. If a mini-excavator can reach the run, work goes fast. Fenced backyards with narrow gates, mature trees, or tight side yards push work toward hand digging — and in compacted East Tennessee red clay, hand digging is slow, expensive work. This single factor explains many "why is my neighbor's quote so different" mysteries.
4. Discharge distance. Collected water has to go somewhere legal — daylight on a downslope, a dry well, or a storm connection. On Knoxville's ridge-and-valley lots there's usually good fall available, which helps. A flat lot that needs a long solid-pipe run or a dry well adds real cost.
5. Obstacles. Tree roots, buried utilities, irrigation lines, and hardscape crossings all slow a trench down. Knox County's karst limestone occasionally shows up as shallow rock — rare in a typical yard drain, expensive when it appears at footing depth.
6. Materials. Washed gravel, filter fabric, and rigid PVC cost more than a roll of corrugated pipe dropped in bare clay. This is the difference between the quote that's suspiciously cheap and the drain that still works in twenty years — most of our french drain repair calls are the cheap version failing.
How to compare quotes (three questions)
When you're holding two or three bids, ask each contractor: rigid or corrugated pipe? fabric-lined trench or not? and where exactly does the water discharge? If a bidder can't answer the third question specifically, they haven't designed a system — they've priced a trench. The cheapest quote that answers all three well is a better buy than a cheaper one that doesn't.
What we quote
We walk the yard, trace where the water is coming from and where it can legally go, and quote a fixed price — if the honest fix is a $900 regrade or a downspout reroute instead of a $4,000 french drain, that's what the quote says. The estimate costs nothing anywhere in Knoxville, Farragut, Powell, Maryville, Oak Ridge, or the surrounding area.