To unclog a downspout, first clear the outlet at the top where the gutter drains, then flush water down from the top. If it backs up, the clog is usually in the first elbow: remove the elbow screws, clear it by hand and reattach. For long or underground runs, use a plumber's snake or a hose with a bladder nozzle from the bottom.
Step by step
Clear the top outlet
From the ladder, pull leaves, needles and cones out of the drop outlet in the gutter.
Flush from the top
Feed a hose into the outlet and turn it on. Water exiting freely at the bottom means you are done.
Tap to locate the clog
If water backs up, tap the downspout from the top down. A dull thud marks packed debris.
Remove and clear the elbow
Most clogs sit in the first elbow below the eave. Remove the screws, pull the elbow, clear it, and reattach with new screws.
Snake long runs
Push a plumber's snake or flexible auger up from the bottom, or use a hose with a bladder nozzle that expands to blast through clogs.
Test underground lines
Disconnect the downspout from any underground pipe and run water into the pipe. If it backs up, the clog or collapse is underground.
Why downspouts clog in Portland and Vancouver
Fir cones, maple seeds and packed needles are just the right size to wedge in a 2x3 inch outlet or elbow. Once one cone lodges, needles stack behind it until the downspout is solid.
Preventing the next clog
- Add an outlet strainer or leaf guard at the top of each downspout
- Upsize to 3x4 inch downspouts on runs that clog repeatedly
- Install gutter guards on runs under conifers
- Flush downspouts at every gutter cleaning, not just the troughs
Frequently asked questions
Can I use a pressure washer to unclog a downspout?
A pressure washer wand can blast loose debris but can also dent thin aluminum and spray water behind siding. A hose and snake are gentler.
What if the clog is underground?
Try snaking from the downspout opening or the outlet end. Roots and collapsed pipe may need a drain specialist. An above-ground extension is a quick workaround.
How often should downspouts be flushed?
At every gutter cleaning, and after the first big fall storm.
Need a hand?
- Downspout Cleaning & Repair: Clogged, crushed or disconnected downspouts cleared and rerouted so water leaves your foundation.
- Gutter Cleaning: Hand-cleaned gutters, flushed downspouts, roof edge cleared and everything bagged and hauled away.
- Gutter Guards: Micro-mesh and screen guards chosen for fir needles, maple leaves and moss, not a one-size pitch.