French Drain Installation: Send Water Away From Your Home

A French drain — a gravel-filled trench with a perforated pipe — collects water that pools in your yard or seeps against your foundation and carries it somewhere safe. Done right, it's a permanent drainage fix; done wrong, it clogs or runs backward. Four fundamentals make it work: map the water, slope the trench, line it correctly, and keep the outlet clear.

How do I plan a French drain?

Map where water naturally collects after rain. Watch your yard during a downpour and note where water pools, where it flows, and where it sits against the foundation. The drain has to intercept that water and lead it to a lower spot. Planning the route around how water actually moves on your property is what makes the drain effective — it's the same instinct behind basement waterproofing.

Why does the slope matter so much?

Everything — dig the trench with a consistent downward slope toward the outlet, generally about 1% (roughly 1 inch of drop per 8–10 feet). Water moves by gravity, so a flat or uneven trench just holds water instead of draining it. Use a level and string line as you dig to keep a steady fall the whole way. Slope is the single most important detail.

How do I line a French drain trench?

Line the trench with landscape fabric and gravel. Lay water-permeable fabric in the trench (it keeps soil and roots from clogging the system), add a gravel base, set the perforated pipe (holes down is the common method for groundwater collection), surround it with gravel, then wrap the fabric over the top before backfilling. The fabric-and-gravel envelope is what keeps the drain flowing for decades instead of silting up.

Why must the drain outlet stay clear?

Make sure the drain outlet is clear and unblocked — the whole system fails if the water has nowhere to exit. The outlet should daylight at a lower point, a dry well, or a storm drain (per local rules), and stay free of debris, soil, and critters (a grate helps). Check it periodically, especially after storms. A blocked outlet backs the whole drain up, undoing all the work.

Track drainage projects

Logging your drainage work and any wet spots helps you manage water long-term. Okoniq Property Hub keeps it with your home maintenance records in one private place. Pair it with foundation crack monitoring.

Frequently asked questions

Do I need to call before digging a French drain?

Yes — call 811 (in the U.S.) to have underground utilities marked before you dig. Hitting a buried line is dangerous and expensive. This is a must before any trenching project.

When should I hire a pro for a French drain?

For drains tied to serious foundation water, long runs, hard digging, or where slope and outlet are tricky, a drainage contractor is worth it. Short yard drains are a doable (if labor-intensive) DIY with careful slope.

Okoniq Property Hub helps homeowners and small landlords keep maintenance, bills, and contractor info in one calm place. Get started free.