If they are overflowing but there’s no obvious blockage in the gutters themselves, then the problem could be a blocked downpipe. Blockages can be caused by almost any kind of debris, including a bird’s nest, a clump of
wet leaves or a ball that enters the gutter and then gets trapped in the downpipes. Typical places a blockage can occur include are at the top of the downpipe, in the middle or above or below any bend.
Downpipes Blocked at the Top
Start with a visual inspection. Use a ladder to look down the top of the rain pipe. If you can readily see that the downpipe is blocked, use a length of wire with one end bent into a hook to snag or clear the clump of debris. Take a hose or pour several buckets of water to flush out any loose material that broke away in the process.
Downpipes Blocked in the Middle
When gutters overflow but there is no visible blockage at the top of the downpipe, then the problem is most likely in the middle. To clear this type of blocked pipe, first try flushing it from the top with a pressure hose.
If water the water still isn’t flowing as freely as it should, try dismantling the pipe. You can avoid having to remove its entire length by tapping it at intervals and listening for a solid sound. Once you’ve pinpointed where the blockage is, you can remove the affected section of pipe and then clear it out with a length of wire. Don’t assume that there’s only one clog; before reattaching the piece of pipe, continue tapping to see if there is any more clumps of debris.
Another tell-tale sign that a downpipe might be blocked somewhere in the middle is water leaking from seams where the pipe has been joined together. If this is the case, you will most likely find the blockage directly below the leaking join.
Should dismantling the downpipe not be an option, use a plumbing snake to locate the blockage. From the top of the downpipe, feed the snake into the opening until it hits the obstruction. Manipulate the plumbing snake until the
debris has been cleared. To ensure that the downpipe is working properly, use a hose to test for flow.