Designing a drain that lasts
Filter fabric wrapped around the stone (not just under it) keeps silt out. Use rigid perforated PVC over corrugated flex pipe where you can — it holds slope and can be snaked if it ever clogs.
- • Holes face down: water enters from the bottom of the pipe.
- • Add cleanouts every 50–100 ft on long runs.
- • Never discharge into a sanitary sewer — it's illegal in most jurisdictions.
FAQ
How much does a French drain cost per foot?
Exterior yard drains typically run $25–60 per linear foot installed; interior basement systems with a sump run $70–150 per foot.
How deep should a French drain be?
18–24 inches for surface water in a yard, and down to the footing (often 3–5 ft) for a foundation perimeter drain.
Can I install a French drain myself?
A short yard drain is a realistic DIY weekend with a rented trencher. Foundation and interior systems involve structural risk and utility locates — hire that out.
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