How much does a French drain cost?

A professionally installed French drain runs about $1,500 to $6,000 depending on length and depth, or roughly $20 to $60 per linear foot. Foundation and interior drains cost more. DIY materials are about $10 to $20 per foot, with the savings in the digging.

Can I install a French drain myself?

Yes, a yard or surface French drain is a doable DIY if you are up for heavy digging. The keys are a continuous slope toward the outlet, landscape fabric to keep silt out, and the pipe oriented holes-down. Renting a trencher makes long runs far easier.

How deep should a French drain be?

A surface yard drain is often 12 to 24 inches deep; a foundation drain goes down to the footing. The exact depth depends on the job, but what matters most is a steady downhill slope of about one percent the whole way to the outlet.

Where does a French drain drain to?

It needs a lower outlet: daylight on a slope, a dry well, a storm drain where permitted, or a pop-up emitter in the yard. The drain only works if water has somewhere lower to go, so picking the outlet comes before digging.

Do I need a permit for a French drain?

A simple yard drain usually does not, but tying into a storm sewer, working near a property line, or major grading can require one. Rules vary by town, so check with your local building or stormwater department before a large project.

UPDATED JUNE 2026

French Drain Cost in Washington

Locally calibrated hire vs. DIY cost data for french drain projects in Washington. Cited sources, permit requirements, and a full build guide, free.

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HIRE A PRO

$1,700–$6,700

Fully installed, labor + materials

DIY COST

$400–$1,600

Materials + rentals, your labor free

Moderate

Requires some construction knowledge and proper planning.

Government Data · Government Data · Submitted Quotes (n=0)

How we got these numbers

National benchmark costs from RSMeans, Angi, Fixr, and HomeGuide are adjusted for Washington using two federal datasets: the Bureau of Economic Analysis Regional Price Parity (RPP) index and the Bureau of Labor Statistics (BLS) Occupational Employment and Wage Statistics. Washington's RPP is 1.1 (national baseline = 100) and its BLS labor adjustment factor is 1.15. Higher RPP means goods and services cost more relative to the national average; the BLS factor scales contractor labor rates to local wage levels. We blend these two adjustments, weighted 40% RPP, 60% BLS labor, to produce the ranges shown above.

adjusted_cost = national_benchmark × (0.4 × RPP/100 + 0.6 × bls_labor_adj)

RPP(Washington) = 1.1 · BLS adj = 1.15

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What's included

Item	Qty	Unit Cost	Subtotal
Perforated drain pipe with sock	50 to 100 ft	$1.5	$150
Drainage gravel	several cubic yards	$45	$270
Landscape fabric	1 roll	$60	$60
Catch basin or pop-up emitter	1 set	$80	$80
Materials Total			$560

Tools you'll need

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TOOLS YOU PROBABLY OWN

Shovel, mattock, and wheelbarrow
Level and string line

TOOLS TO RENT OR BUY

Trencher rental
Rent a trencher for long runs to save your back

Build sequence

1
Plan the route from the wet area to a lower outlet, and call to locate utilities first.
COMMON MISTAKE
Digging before calling 811 risks hitting buried lines.
2
Dig the trench with a continuous slope of about one percent toward the outlet.
COMMON MISTAKE
A flat or back-sloped trench holds water instead of draining it.
3
Line the trench with fabric and add a gravel base.
4
Lay the perforated pipe holes-down, cover with gravel, and wrap the fabric over.
5
Top with soil or sod and confirm water flows to the outlet.

Permits and code requirements

PERMIT REQUIREMENTS

Permit rules for french drain vary by city and county in Washington. Most structural, electrical, plumbing, or mechanical work needs a permit and an inspection. Confirm with your local building department, or see the Washington guide for specifics.

PERMIT THRESHOLD

Varies by municipality

Disclaimer: Always verify permit requirements with your local building department before starting work. Requirements vary by municipality and are updated periodically.

Frequently asked questions

NEXT STEPS

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UPDATED JUNE 2026