French drain vs dry well: which fits your yard?
Should I use a French drain or a dry well?
Choose a French drain to collect and move water; choose a dry well only where soil can absorb it. Published planning rates as of Nov 2026 are $20–$45 per linear foot for a regional installer’s French drain, versus $300–$1,500 per dry well. Soil suitability and the discharge route decide which works.
Evidence: S&S Excavation; HomeGuide; Northern Virginia Soil and Water Conservation District / Fairfax County. Researched Nov 2, 2026; original rate-source dates are listed below.
Moving water and absorbing it are separate decisions
| Choice | Use it for | Reason to reconsider |
|---|---|---|
| French drain | Collecting subsurface water along a wet strip and conveying it elsewhere. | There is no viable discharge route or the water is only fast surface runoff. |
| Dry well | Receiving collected runoff in suitable soil away from structures. | Infiltration is poor, groundwater is high or bedrock is shallow. |
| Both together | Collecting water remotely and delivering it to a tested infiltration location. | The proposal has no testing, overflow route or clear connection scope. |
A dry well is not automatically the cheaper alternative: it solves a different part of the job. The French drain pricing guide explains trench scope; the dry well cost guide explains the receiving package.
Test the receiving area before choosing storage
As of Nov 2026, the conservation district’s runoff guidance calls for infiltration testing before a dry well and flags poor infiltration, high groundwater and shallow bedrock as problems. A larger buried container does not by itself make water soak into unsuitable soil.
Use the dry well sizing and permit guide to prepare the site questions. Ask how the design handles overflow when inflow exceeds infiltration; avoid a quote that promises storage but never describes its destination after the well fills.
Compare the whole route on each quote
French drain pricing uses length; a dry well uses a unit package. Ask bidders to show collection trench, conveyance pipe, infiltration unit, testing, spoil removal and restoration separately, with overlaps identified; do not compare a short trench with a complete collection-and-storage design.
A homeowner can trace the wet area and roof-water entry points before requesting excavation. Have a drainage professional assess the receiving soil and elevations when the only proposed outlet is underground storage; do not excavate a test hole before utility checks.
A downspout extension may solve a concentrated roof-water problem without either installation. Review where gutter water should go and the local approval and 811 checklist before approving the larger scope.
Frequently asked questions
Can a French drain empty into a dry well?
Yes, where the receiving soil, groundwater conditions and approved design support infiltration. The dry well is the receiving component; the French drain still has to collect and convey the water.
Is a dry well suitable for clay soil?
Do not assume so. Test infiltration at the proposed receiving location and have the design assessed; storage without adequate drainage can remain full.
Does a French drain need a dry well?
No. It may discharge to another suitable approved outlet. Choose a dry well because the receiving conditions support it, rather than treating it as a required French drain accessory.
Which option needs less excavation?
That depends on the collection length, receiving depth, access and spoil disposal. Compare a route sketch and excavation scope for each design instead of judging from the equipment name.
Sources
- S&S Excavation: S&S Excavation — published Kansas City French drain rates. Rate source checked 2026-10-26.
- HomeGuide: HomeGuide — drainage system installation cost. Rate source checked 2026-10-26.
- Northern Virginia Soil and Water Conservation District / Fairfax County: Control Heavy Runoff — Solving Drainage and Erosion Problems. Accessed Nov 2, 2026.
Source scope and rate limitations: drainage sources and methodology.