Estimate pipe, gravel, fabric, and total cost for a French drain installation. Compare DIY and professional pricing.
LotSite starting assumption
LotSite starting assumption
LotSite starting assumption
LotSite starting assumption
LotSite starting assumption
The prices filled in here are LotSite starting assumptions, not quotes and not sourced prices. Prices differ by region and supplier, so type in a local quote and the estimate will use it.
Need to plan your drain path? View your yard on satellite imagery with LotSite →
DIY vs professional installation costs for standard 4-inch drains.
Dollar figures here use LotSite starting assumptions, not quotes and not sourced prices. Use the calculator above with a local quote for your own number.
| Length | Gravel Needed | DIY Cost | Pro Cost |
|---|---|---|---|
| 25 ft | 0.7 cu yd | $100 | $550 |
| 50 ft | 1.4 cu yd | $199 | $1,100 |
| 75 ft | 2.1 cu yd | $299 | $1,650 |
| 100 ft | 2.8 cu yd | $399 | $2,200 |
| 150 ft | 4.2 cu yd | $598 | $3,300 |
| 200 ft | 5.6 cu yd | $798 | $4,400 |
A French drain is a gravel-filled trench with a perforated pipe that collects and redirects water away from problem areas. It is one of the most effective solutions for wet yards, soggy spots, and foundation drainage issues.
The key to a successful French drain is proper slope. The trench must slope at least 1 inch per 8 feet (1 percent grade) toward the outlet point. Use a laser level or string level to verify consistent slope before laying pipe. The outlet can be a dry well, a storm drain, or a lower area of your property.
Use LotSite to plan your drain path on satellite imagery. Viewing your property from above helps you identify the best route from the problem area to the outlet point, and estimate the total length needed.
The gravel figure assumes a 4-inch pipe in a trench 12 inches wide and 18 inches deep, with 0.75 cubic feet of gravel per foot, which leaves the top of the trench for soil and sod. If you fill the trench with gravel to the surface, a 12 by 18 inch trench holds 1.5 cubic feet per foot, double the figure above. The 6-inch option assumes a wider trench at 1.25 cubic feet per foot. Gravel is priced at $50 per cubic yard as a bulk delivery; bagged drainage rock from a home center costs much more per cubic yard, so for a short run price the bags instead.
Pipe at $1.50 per foot, fabric at $0.60, and fittings at $0.50 cover the trench itself: couplings, a few elbows, and an end cap. They do not cover the outlet. A surface drain basin where water enters, a pop-up emitter where it leaves, or a dry well when there is nowhere lower to send it are separate purchases, and an outlet with nowhere to drain is the usual reason a French drain stops working. Add those as line items before comparing quotes.
The slope line is the minimum total drop over your length at 1 inch per 8 feet. If the ground between the wet spot and the outlet falls less than that, the trench has to get deeper toward the outlet, which means more digging and more gravel than the per-foot figure, or a different outlet. Check the grade with a string line and a line level before you buy anything. The length you measure on the map is horizontal distance, so measure the drop on the ground.
The professional figure of $22 per foot is a single midpoint, not a quote. Rock, roots, hand digging where a trencher cannot reach, and putting lawn or pavers back over the trench all push it up, and a long straight run in open soil can come in under it. Ask any installer for the price per foot and what it includes, so the comparison with the materials figure here is like for like.
Enter your address to view your yard and plan the best drain route.
Also check out our gravel calculator and retaining wall calculator