Clogged Downspout or Clogged Gutter? How to Tell From the Ground

Start here: where the water leaves tells you which one is clogged

Watch from about 20 feet back, not from underneath. A packed gutter overflows along its length — a curtain off the front lip, fairly even, starting a minute or two after the rain picks up. A plugged downspout overflows in one place: the corner directly above the outlet, usually a rope of water rather than a curtain, while the rest of the run stays dry until water backs up far enough to reach it. Then close your eyes and listen. A working downspout is loud; you hear water hitting the bottom elbow and the splash block. A plugged one is silent, or gurgles for ten seconds and quits. Silent downspout plus overflowing gutter is the single most reliable ladder-free call there is. A downspout that runs hard and still can't keep up is usually undersized, not clogged — a 2x3 handles roughly 600 square feet of roof, a 3x4 about 1,200.

Four tests you can run from the ground on a dry day

Rain here is scarce enough that waiting for it is a bad plan, so test dry. First, the knuckle test: rap the downspout every 12 inches from the kick-out up as high as you can reach. Empty aluminum rings; a packed section thuds flat. The height where the tone changes is the top of the clog, and nine times out of ten that is the bottom elbow or the upper elbow at the drop. Second, the daylight test: pull the bottom elbow — most are friction-fit or held by two 1/4-inch hex screws — and look straight up with a flashlight. Sky means clear. Third, the hose test: feed a garden hose up from the bottom. It will travel 8 to 10 feet before it hangs up, and where it stops is the blockage. Fourth, tape a phone to a paint-roller extension pole, hit record, and walk the run. That costs nothing and shows you the inside of the trough.

Reading the evidence after the rain stops

Dirt streaks running down the outside face of the gutter mean water has been sheeting over the lip for a while — that is a trough problem. A trench eroded into bark or mulch under one corner, with a fan of shingle grit in it, means volume has been leaving the system at that spot. Now look at the kick-out itself. A cone of shingle granules and silt on the splash block means water is moving through the downspout, so the downspout is fine. Dry, clean concrete under a kick-out after a real storm, while the rest of the yard is soaked, is a blocked downspout, full stop. Check the downspout body too: a bulged seam, a rust line at a joint, or a vertical wet stripe on the siding behind it all mean water has been standing inside. In January, ice at the kick-out or a downspout that is solid and cold to the tap says the same thing.

The Treasure Valley version: why our timing is different

Boise averages roughly 11.7 inches of precipitation a year, which is exactly why gutters here stay clogged for months without anyone noticing — there is no rain to reveal it. The reveal is a summer thunderburst or the first real storm in November. Debris arrives in two waves: cottonwood fluff plus locust and maple seed from late May into June, which mats into a felt that water runs over rather than through, then a compressed leaf drop between late October and mid-November. Add ag and construction dust, which settles into a silt that packs an outlet without ever looking like a clog from the ground. Winter is the expensive part. With something like 120 nights a year below freezing, a downspout holding water freezes into a solid column, the gutter has nowhere to drain, and it dumps over the low point onto whatever walkway happens to be underneath.

When you should not pay anyone, us included

If the knuckle test puts the clog in the bottom elbow, that is a five-minute fix and it is yours. Pop the elbow, pull the wad of leaves — or the tennis ball, or the wasp nest — put it back, done. Paying $199 for that is a waste of your money. Same story if one downspout is slow and the rest of the house drains fine: clear the elbow and re-test before you book anything. Two honest limits while you are down there. Do not run a pressure washer up a downspout from the bottom; 2,000 PSI inside a six-square-inch aluminum tube pops seams, and you will be buying a downspout. And a leaf blower jammed into the top of a drop tube mostly packs wet debris tighter. What actually earns a service call is a whole-house condition, a second-story run, or a trough you cannot see into.

When it is neither — and the version nobody can clean

Three situations look like a clog and are not. Sag: water spilling at one point mid-run while the gutter is visibly clean is a pitch problem. Gutters want about a quarter inch of fall per 10 feet toward the outlet, and one hanger backing out of the fascia kills it. Cleaning will not fix that; a hanger will. Guards: fine mesh loaded with cottonwood fluff sheds water off the top, so you get a waterfall while the trough behind it is bone dry — the guard is the clog, and it has to come off or be cleared from above. Then the one that ends the conversation: downspouts tied into a buried 3- or 4-inch line running to a dry well or the curb. If that line is collapsed or full of roots, no gutter cleaner fixes it from the top. That is a drain contractor with a jetter or a shovel, and we will tell you so.