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French Drains & Drainage in Seattle, WA

Water in the basement, a spring that never dries in the yard, or a foundation that weeps every November? We connect Seattle and Eastside homeowners with local drainage specialists — French drains, sump pumps, basement waterproofing, and foundation drainage.

Seattle Water Doesn't Take the Winter Off

If you're looking for a French drain, the ground has probably already made its point — a puddle in the basement after every atmospheric river, a lawn that squelches into April, or a musty smell that shows up with the first real rain and stays until July. Seattle is one of the hardest cities in the country on a foundation: rain most of the year, heavy glacial-till and clay soils that trap water instead of draining it, and hillside lots that funnel uphill runoff straight at the house. Water collects against the foundation, pressure builds, and it finds the nearest seam.

A drainage system relieves that pressure — collecting the water in gravel-bedded pipe and moving it somewhere harmless before it reaches your walls. Which system depends on where the water is: your yard, your footings, or inside a finished basement. This site gets you to a specialist who does drainage as their trade, not as a line item under general landscaping.

Drainage Services for Seattle & the Eastside

Why It Floods Here Specifically

The rain doesn't stop, so the ground stays saturated

Seattle averages rain on roughly 150 days a year, most of it a slow soak rather than a downpour. Soil never fully dries between storms from October to May, so the water table sits high and the ground around your foundation stays full. A dry-climate house gets a break; here the pressure is close to constant for half the year.

Glacial till and clay hold water against the house

Much of the Seattle area sits on dense glacial till and clay — soils that drain slowly and trap water rather than letting it percolate down. Rain that lands near the foundation has nowhere to go, so it banks up against the walls and footings. It's the reason a French drain works so well here: it gives that trapped water the escape route the soil doesn't.

Hillsides send water toward the low house

From Magnolia to the Issaquah plateau, a lot of local homes sit on slopes. Uphill ground sheds its water downhill — and if your house is downhill, it arrives at your foundation. A curtain or interception drain uphill of the house cuts that flow off before it gets there.

Older basements are the usual victims. Homes built before modern footing drains — much of Seattle's pre-1980 stock — often have no perimeter drainage at all, or a clay tile system that's collapsed or clogged with roots. When those fail, the interior perimeter drain is the standard fix.

Signs You Have a Drainage Problem, Not Just a Wet Day

One wet basement in a record storm is bad luck. A basement that's wet every winter is a drainage problem, and it gets worse — and more expensive — the longer the water works on the foundation.

Get a Fast Response From a Local Drainage Pro

Tell us what's happening and a local drainage specialist serving Seattle and the Eastside will get back to you quickly — usually the same day.

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Seattle Drainage Questions, Answered

How much does a French drain cost in Seattle?

An exterior or yard French drain commonly runs $3,000–$10,000; an interior perimeter drain with a sump — the wet-basement fix — is usually $6,000–$15,000. Length, depth, and where the water can exit drive the number. Full breakdown in the cost guide.

French drain or full basement waterproofing — which do I need?

If the water is in the yard or against the footings, a French drain handles it. If it's coming through a finished basement wall or floor, that's basement waterproofing — usually an interior perimeter drain plus a sump. A specialist cameras and assesses before quoting either.

Will a French drain fix my sump pump running non-stop?

Often, yes — a sump that never rests usually means water is reaching the basement faster than it should, and better perimeter or exterior drainage cuts the inflow. Sometimes the pump itself is undersized. A sump assessment sorts out which.

Do drainage projects need a permit in Seattle?

Yard and perimeter drainage often doesn't, but work that ties into the city storm system, alters grade near a slope, or touches a critical area (common on Seattle's steep lots) can. A legitimate contractor knows the local thresholds and pulls what's required — inside the city or in the county.

Read the full cost guide →