A clogged downspout looks like a clogged gutter from the ground, and that’s the problem. The gutter overflows, the homeowner has the gutter cleaned, and the next storm it overflows again because the water still has nowhere to go. The downspout is the bottleneck, and it’s where pine needles, oak leaves, roof grit and the occasional tennis ball end up.
Downspout clearing is included in every gutter cleaning we do, but it’s a distinct problem with its own signs and its own fixes, and on a lot of homes here the hard part is buried in the yard.
What are the signs a downspout is clogged?
During rain, the gutter overflows at the downspout end, or along the whole run, while the downspout outlet dribbles or runs dry. Water leaks from an elbow or seam partway down, because the downspout has filled from the clog upward and found the weakest joint. Water sheets down the wall behind the downspout. You hear a sloshing or gurgling in the gutter.
In dry weather, the test is a hose. Run water into the gutter near the downspout at full pressure and watch the outlet. Clear downspouts flow within a few seconds. Blocked ones back up in the gutter, or you get a trickle. If the water backs up and then suddenly surges, the clog is partial and just got pushed further down, which usually means it’s now packed harder at the next elbow.
Other signs: a downspout that’s bulging at an elbow, which means it’s been full of wet debris and froze or just deformed under the weight. A downspout with a plant growing out the bottom. Staining on the wall around the seams. And a bird or rat activity at the top of the downspout, because it’s full of nest material.
Where do downspouts clog?
Almost always at the elbows. A standard downspout has an elbow at the top where it turns from the gutter outlet into the wall, another at the bottom where it kicks out to the splash block, and sometimes one or two more where it jogs around a roof step or a second-story offset. Each elbow is a spot where debris has to change direction, and needles and leaves pile up there.
Two-story homes in Encino and the south Valley hills often have a downspout that drops from the upper gutter onto the lower roof, runs across the lower roof, then drops again. That’s four or five elbows. Every one is a clog point.
Pine needles are the worst. They’re long, they lie flat, and they interlock. In Sylmar and Tujunga under the foothill pines, we pull plugs of needles out of downspouts that are a foot long and hard as a broom. Oak leaves pack tight too. Roof grit sinks to the bottom elbow and forms a sludge.
How do I clear a downspout?
Start from the top. With the gutter cleaned so nothing else gets pushed in, run a hose into the outlet at full pressure. Sometimes that’s enough. If the clog is at the top elbow, you can often reach it by hand from the gutter.
If the flush doesn’t work, go to the bottom. Remove the extension or splash block, and look up the bottom elbow with a flashlight. A plumber’s hand snake or a long, flexible rod works up the downspout from the bottom and breaks the plug. Tap the elbows with a rubber mallet or the heel of your hand to loosen packed material. Don’t hit them with a hammer. Aluminum dents.
If neither end works, the bottom elbow comes off. It’s usually held by one or two screws and a strap. With it off, you can get at the vertical run with a rod or a pressure nozzle and push the plug down and out. Then it goes back on.
Anything above the first story is ladder work, and everything in the safety guide applies.
What if the downspout goes underground?
This is where it gets harder, and it’s common here. Most of the tract neighborhoods built since the 1980s in Valencia, Stevenson Ranch, Porter Ranch, Simi Valley and the Conejo Valley have downspouts that drop straight into a pipe at grade, usually a three or four inch PVC or corrugated line, that runs under the lawn to a curb outlet or a drain grate near the sidewalk. Hillside homes often have the same thing, with long runs down the slope.
The underground line clogs the same way a downspout does, plus a few ways of its own. Silt and roof grit settle in low spots and flat runs. Roots find the joints and grow in. Corrugated pipe collapses under a driveway or where a tree root has lifted it. The curb outlet gets crushed by a car tire or covered by a landscape crew.
To test it, find the outlet at the curb. Run a hose into the downspout at full flow and see if water comes out at the street within a minute or so. If it does, you’re fine. If the water backs up the downspout and comes out at the bottom elbow, the line is blocked.
Clearing a buried line means snaking it from the downspout end or the curb end, or having it jetted with a high-pressure hose. A drain plumber does this. If the snake hits a hard stop that doesn’t clear, the pipe has probably collapsed at that point and needs to be dug up and replaced.
If a blocked underground line can’t be fixed before the rain, disconnect the downspout from the pipe and set a splash block or an extension under it so the water goes on the lawn. That’s better than water backing up against the slab. What clogged gutters actually damage has more on why the slab edge matters.
How do I keep downspouts from clogging?
Keep the gutters clean, which keeps the supply of debris down. That’s the main thing, and how often to clean gutters sets the schedule.
Downspout strainers, the wire cage that sits in the gutter outlet, are a mixed bag. They stop leaves and needles from entering the downspout, which is good. But they catch that debris right at the outlet, and if nobody clears them, they dam the gutter. On a lot with pines, a strainer clogs in weeks. Use them only if they’re going to be cleared regularly.
Gutter guards do the same job better because they keep debris out of the whole system. Our guard guide compares the types against local trees.
For underground drains, a cleanout fitting at the base of the downspout, which is a short vertical pipe with a removable cap where the downspout meets the buried line, makes future snaking easy and gives you an overflow point if the line blocks. If you’re installing new gutters or replacing downspouts, ask for one. Leader heads and rain chains are on our products page, and a leader head with a basin at the top of the downspout also gives you an overflow point and a spot to catch debris where you can see it.
What we do
Every cleaning includes a flush of every downspout, and if one is blocked we clear it from the top, the bottom, or by pulling the elbow. Where a downspout ties into an underground drain, we test flow to the outlet and tell you if the buried line isn’t taking water. We don’t dig up drain lines, but we’ll tell you exactly where the problem is so a plumber can go straight to it.
Call (818) 913-1626 Monday through Saturday 7am to 7pm, or request an estimate. Members on the recurring plans get downspouts flushed on every scheduled visit, so a clog gets caught before the storm instead of during it.