Underground Downspout Drainage in Seattle & King County WA
Protect your foundation and landscaping by moving roof runoff underground — the right way.
We install buried downspout extensions that keep water away from your home, stop pooling at the foundation, and prevent flooded crawlspaces.
Why Underground Downspouts Matter
Gutters Aren’t Enough — It’s Where the Water Goes That Counts
When your gutters dump water right next to your house, you’re one storm away from:
Foundation cracks
Wet crawlspaces
Mold and mildew
Washed-out landscaping
Erosion along paths and patios
Underground downspout drainage solves the problem by moving stormwater where it won’t cause damage — quietly, efficiently, and permanently.
What’s Included
What’s in a Sandbagger Downspout Drainage System?
We don’t just bury pipe — we build systems that work long-term. Every install includes:
Site evaluation and grading assessment
Custom routing for proper slope and flow
Durable PVC or corrugated pipe
Downspout connection and sealed entry
Optional cleanouts for easy maintenance
Tie-ins to drywells, French drains, or daylighting
Full site restoration after install
We design each system for the PNW’s heavy rainfall and unique soil conditions.
Perfect For Homes With
Do You Need This System? You Might If…
Your gutters pour water near the house
You have standing water along the foundation
The soil near your home stays soaked for days
Your crawlspace or basement smells musty
Water is washing out garden beds or mulch
You’re seeing erosion near patios or paths
Why Homeowners Choose Sandbagger
We Build Systems That Don’t Fail
Trusted by 200+ homeowners across King County
Woman-owned and RainWise-certified
Washington State Certified Erosion & Sediment Control Lead
Designed for long-term performance — not band-aid fixes
We restore your yard and leave it clean
Where We Install French Drains
Underground Downspout Drainage in King County WA
Seattle
Burien
RENTON
KENT
DES MOINES
SHORELINE
TUKWILA
Bellevue
Federal Way
& surrounding areas
REVIEWS
Homeowner Testimonials
Brian S., Federal Way
After the system was installed, no more water near the foundation. Looks great and works even better.
Monica T., Bellevue
They buried all four of our downspouts and connected them to a drywell. Couldn’t be happier.
FAQs
Downspout Drainage FAQs
Can you connect to existing French drains or drywells?
Yes. We often tie new downspout lines into existing drainage systems.
Will I need permits?
Not usually for residential downspout drainage, but we’ll confirm with your city or county and handle it if needed.
How long does it take?
Most buried downspout systems are installed in 1 day.
Let’s Get That Water Away From Your House
Contact us for a free on-site quote and find out what it’ll take to protect your home the right way.