The short answer
Start by finding where the water stops. If the gutter overflows at one point, the blockage is at that outlet. If water backs up from below or the pipe is full, it is lower down. Clear what you can reach from the ground with a hose or a drain rod, never from a stretched ladder. A pipe that stays blocked needs checking at height.
Work out where it is blocked
Before you clear anything, find the blockage. The downpipe is the vertical pipe that takes rainwater from the gutter outlet down to the drain, and a block can sit anywhere along that run. Pouring water down from the top and seeing what happens is the quickest test, but start by watching it rain, or run a hose into the gutter and observe.
- Water pours over the front of the gutter near the outlet. The block is at the top, where leaves, moss and roof grit collect around the outlet or in the pipe's first section.
- Water runs down the pipe but spills at a joint or at the shoe. The block is lower, often in a bend or where the pipe meets the drain.
- The pipe is full and slow to empty. There is a partial block, usually in the shoe, the angled piece at the foot, or in the gully below.
- You hear gurgling or water splashing inside the wall. The pipe may be cracked or a joint may have failed, which is a repair rather than a clean.
Tap down the length of the pipe with your knuckles. A hollow sound turns dull where it is packed with debris, and you can often locate a heavy section by feel. If the pipe is cast iron, tapping with a small mallet works better, but go gently because old cast iron is brittle.
Work out whether the pipe is shared before you go further. Our page on a shared gutter on a terrace explains what to do if your neighbour's roof drains into the same run.
Clearing it safely from the ground
Most downpipe blockages at the bottom can be cleared with your feet on the ground, which is by far the safest way. Start there before even considering the top.
Lift out the grating over the gully, if there is one, and scoop out the silt and leaf mould by hand with gloves on. Check the shoe and the first bend. A bent length of stiff wire or a drain rod with a soft plug end will push through a soft block, and a garden hose on its strongest setting will flush it through. Run the water from the top of whatever you can reach, not from the bottom, so you push the debris down towards the drain rather than packing it tighter.
Should the water back up in the gully instead of in the pipe, the blockage has travelled into the drain. That is a drainage problem rather than a roof one, and a drainage firm with proper equipment is the right call.
Do not use caustic chemicals in a downpipe. They do little against leaf and moss, and they can damage a cast iron or plastic joint. Avoid forcing a rod hard against a bend, since it can crack an older pipe or push a joint apart behind the wall where you cannot see it.
When the block is at the top
Blockages at the outlet are the most common sort. Leaves, moss that has slid off the roof, grit washed from the covering, and sometimes a bird's nest all gather at the point where the gutter narrows into the pipe. Look at the wall below: a dark stain or a green streak shows where overflow has been running.
Clearing it means getting up to gutter height. For a single-storey eaves, a stable ladder with a stand-off arm, footed on firm ground and tied or held, is a sensible tool. Stay low on the ladder and do not lean out sideways. For anything higher than the ground floor, or if there is no safe footing, do not attempt it yourself. Falls from ladders cause serious injuries, and a clear gutter is not worth one.
At the outlet, scoop debris out by hand into a bucket rather than flushing it into the pipe. Then run water in to check it drains. A gutter that clears and then refills within weeks suggests the roof above is shedding moss or the gutter is undersized or poorly fixed. Our page on how often to clean gutters sets out a sensible routine.
Damage a blocked downpipe can cause
A downpipe that stays blocked does not just overflow. Water has to end up somewhere, and the options all hurt the building.
Overflow tips over the front edge of the gutter and streaks the wall, staining stone and brick, and soaking the base of the wall. In winter the water freezes in the pipe, splitting joints or cracking a plastic pipe along its length. It can soak the fascia and eaves timbers, which then rot from the outside in. On older houses with solid walls, a wall that is repeatedly wetted may show damp inside.
Along the eaves runs the fascia, the board that carries the gutter brackets. If water has been running behind the gutter for a season, it is worth having the board probed for softness. Our page on fascia board replacement explains what we look for and how a damaged length is renewed.
On a roof with a parapet gutter or box gutter, a concealed channel set behind or within the wall, a blocked outlet is more serious. Here the water can only escape through the structure, and these need a roofer who can work at height safely.
When to call a roofer
Some blockages need more than a bucket and a hose. Call for help when the pipe is on a high wall, when it stays blocked after you have cleared the bottom, when the pipe is cracked or leaking at the joints, or when a bend is packed solid. Also call when the gutter has sagged so the outlet sits proud, because water then pools instead of draining and the same block returns.
A roofer working at height can clear the outlet, flush the pipe from the top, and check the fixings and joints at the same visit. If a length of pipe is cracked or the brackets have failed, it can be replaced, matching the existing material where the house calls for it. Cast iron stays cast iron, and plastic can be swapped for plastic.
MyBuilder's 2026 guide gives typical UK guttering costs of £30 to £70 per metre, with scaffold adding £20 to £40 per square metre where access is needed. A simple clear-out is a much smaller job than a replacement. Your fixed quote follows the survey.
A survey from us is free, and we photograph the outlet, the joints and the brackets so you can see them yourself. Study the joint photographs closely, since a socket that has slipped apart lets water run down the wall even after the blockage is cleared. Other roofline jobs are listed on our gutters, soffits and fascias page.
