French Drain vs Swale: Which One Do I Need?
How to choose between a subsurface french drain and a shallow surface swale for yard drainage, with cost, maintenance, and flow-capacity trade-offs.
Use a swale when you have room for a shallow surface channel and the runoff is intermittent (rainstorms). Use a french drain when the water is subsurface (springs, saturated soil), or when a swale is not practical because of a walkway, patio, or lawn use.
Swale
A shallow, vegetated channel that moves surface water by gravity. Cheap, low maintenance, easy to grade. Requires space and a good outlet. Not appropriate for foundation drainage or persistent wet spots.
French drain
A gravel-filled trench with perforated pipe that collects subsurface water and carries it to daylight or a dry well. Handles springs and persistent wet spots. More expensive and can silt up over time.
When to use both
For a wet backyard with poor natural drainage: a shallow swale to move surface stormwater, plus a french drain along the low side to catch the persistent seepage. The two systems handle different water sources.
Ready to run the numbers?
Use the french drain calculator to get a specific quantity for your project.
Open the french drain calculator →Related guides
Last reviewed . Educational estimates only; local conditions and codes take precedence. Consult a qualified professional for site-specific decisions.