How to Unblock a Gutter Downspout

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Fall leaves on a roof (Photo: @RLTheis via Twenty20)
If you in a neighborhood with mature foliage and trees, cleaning gutters is a cumbersome task that has to be performed annually, if not more frequently. Blockages cause water to pour over the edge of the eavestroughs rather than being channeled away from the foundation.
Going up on the ladder or roof isn’t exactly one of the most enjoyable tasks for homeowners, but it’s necessary. What happens when you’ve cleaned your gutters but water still flowers over the edge of the eaves? Chances are you have a blocked downspout.
Although there’s a clog somewhere in the middle of a downspout, don’t worry. It’s usually less troublesome to deal with than you might think.

What can cause a downspout to become blocked?

When you’ve cleaned out your gutters, those decomposing leaves and bits of roof asphalt are often the culprits that restrict flow to the ends where it can drain away. It’s exactly that same material that can plug up a downspout.
When you look at a downspout, the smooth sides might be deceiving. How does all that debris get caught up inside to plug it up completely? It’s possible that the tension of a packed clump of gooey rotting leaves, dirt, and asphalt has just wedged itself in place. In most cases, the blockage occurs where a screw enters into the drain or there’s a join, or it could be that a slightly squashed section gathers the junk.
No matter how it happens, unblocking a gutter downspout can be attempted in the same way.

How to clear a blockage in a downspout

How you clear a blockage depends almost exclusively on getting access to it safely. Always use a sturdy ladder when working at heights, and wear a safety harness if possible to prevent accidental falls, especially if you’re not comfortable working on the roof.

Locate the blockage

You might be able to find where the blockage has lodged itself by looking into the downspout from up top using a flashlight. However, if it’s lower down or if you have a two-storey home, this probably won’t be helpful. Instead, tap on the downspout from top to bottom, listening for a dull, dampened sound rather than hollow. This is where your blockage is. Mark it somehow, like with a piece of masking tape.

Break up the blockage

Most blockages can be broken up easily with a stiff piece of wire. If it’s close enough, an unwound coat hanger is an excellent, low-cost solution. Another option can be 14/2 household electrical wiring you have laying around. Fashion a hook in the end of the wire, jam it through the blockage, and pull to break it up. The debris should fall through the downpipe, which you can then flush out with a water hose.

Remove the downspout

Some blockages can be more troublesome, for example if you have a rodent that’s lodged itself in the downspout and perished. It may be necessary to remove the section of downspout from your house and push it out.
Don’t attempt this while the downspout is on your house. Odds are that you’ll just push the blockage further down rather than clearing it, and it can put unnecessary strain on the fasteners and rather delicate downspout material.
Most eavestroughs and downspouts are fastened using self-tapping #2 Phillips screws.

Call a plumber

In the event you can’t restore flow through your downspout using these methods, it could be time to call a plumber. They’ll use a plumber’s auger to break up the blockage and get your downspouts flowing again.