Gutters collect the water, but the downpipe decides where it ends up. It takes everything the roof sheds in a storm, carries it down the wall and hands it to a drain or a soakaway. If any link in that chain fails, the water goes somewhere else: down the brickwork, into the ground against the wall, or over the top of the gutter.
That makes downpipes easy to overlook and expensive to ignore. This guide covers the parts of a downpipe system, the materials, why offsets and bends cause trouble, what happens at the bottom, and when a replacement is worth doing. It belongs to our wider gutters, soffits and fascias work, and pairs naturally with the guide to leaking gutter joints.
The parts of a downpipe system
A downpipe looks like a single tube, but it is a kit of parts. At the top, an outlet in the gutter drops water into the pipe. If the pipe has to dodge a wide eaves overhang, an offset, made of two bends joined by a short length, carries it back to the wall. Straight lengths run down the face, held by clips or brackets fixed to the brickwork. At the bottom, a shoe bends the pipe outwards to discharge into a gully, or the pipe connects directly into the underground drain.
Some older houses use a hopper head instead of a plain outlet, a funnel-shaped box that catches water from a gutter or a waste pipe and feeds it to the downpipe. Hoppers are common on Victorian houses and in cast iron, and they are a favourite place for leaves and sediment to collect.
Each joint is a place where something can go wrong. Push-fit plastic joints rely on a rubber seal and a socket. Cast iron joints are caulked or bolted. A pipe that has been cut short, or fitted without a proper socket, leaks at that point and stains the wall.
What is the difference between a shoe and a hopper?
A shoe sits at the bottom of the pipe and bends the discharge away from the wall. A hopper sits at the top and collects water from a gutter, a waste pipe or a flat roof outlet.
How many downpipes should a house have?
It depends on the roof area and the gutter layout. A longer run, or a roof with a large catchment, needs more outlets so one pipe is not asked to carry too much.
Materials: plastic, cast iron, aluminium and steel
Most houses built in recent decades have uPVC downpipes, available in round, square and rectangular sections. They are light, cheap to fit and do not rust. They can become brittle with age, particularly in strong sunlight, and a pipe that has been knocked or has frozen with water inside can split along its length. Colours can fade or chalk over time.
Cast iron downpipes belong to older houses and are often paired with cast iron gutters. They are heavy, hold their shape and take decorative brackets, but rust from the inside and can crack if a blockage freezes. Our page on cast iron guttering goes into how the older system behaves.
Aluminium downpipes are lighter than iron, do not rust and can be powder-coated in many colours. They are commonly used where a long-lasting and neat finish is wanted, and cast aluminium versions copy period profiles.
Some houses of the mid-twentieth century were fitted with asbestos cement rainwater goods. Old rainwater pipes of this material can be taken down by trained, non-licensed workers if they come away whole and are not snapped or crushed. If a pipe might be asbestos cement, leave it whole and let us inspect it before anyone cuts or drills.
Is plastic good enough?
For most modern houses, yes. It works well when the brackets are correctly spaced and the joints are clean and seated. Poor fitting is more often the cause of failure than the material.
Which material lasts longest?
Metal systems tend to last longer when kept painted and clear, but lifespans vary with exposure and upkeep. Our answer on how long guttering lasts gives typical ranges.
Offsets, bends and where blockages begin
Most downpipe blockages sit at a bend. Water carries leaves, moss, grit and the odd tennis ball from the gutter, and a straight pipe passes it through. An offset slows it down. The lower bend of the offset is where debris stops, and over a season it builds into a plug.
A plugged pipe gives itself away in a storm. Water slops over the lip of the gutter above the outlet, or pours out of an offset joint and runs down the wall. In winter the standing water freezes and can split a plastic pipe or crack iron. When the pipe thaws, the split begins to leak.
Where possible, the best offset is a gentle one, with long, sweeping bends rather than tight elbows. Some older houses have deep eaves, and the offset is unavoidable, but the angle can be chosen to help water through. A gutter guard on the outlet or a leaf trap in the first bend can reduce the debris reaching the pipe.
If water pours out of the middle of a downpipe rather than from the bottom, suspect a blockage in the pipe below that point, not a leak at the joint.
How do I clear a blocked downpipe?
From the top, with a gloved hand or a scoop, then flushing with a hose. Rods from the bottom can push the plug upwards. Our answer on a blocked downpipe goes through the options.
Can a wasp nest or bird nest block a pipe?
Yes. Birds sometimes nest in hoppers and open outlets. Nesting birds are protected, so mention any activity before work starts.
Brackets, clips and fixing to the wall
A downpipe weighs very little when empty and a lot when full, so fixing matters. Plastic pipes are held by clips screwed into the wall at intervals, with a clip near each joint and extra support at bends. Metal pipes sit on ears or brackets that bolt into the masonry.
Poor fixing is a common reason for rattling, leaning and joint leaks. A pipe fixed too tightly cannot expand and contract with temperature, and a pipe fixed too loosely sags until a joint pulls apart. Rusted screws, loose plugs in old brickwork and brackets that have worked free are all everyday faults.
Fixing into old brickwork can be fiddly. Soft mortar crumbles, and pipe ears set into a crumbling joint pull out under the weight of a full pipe. We use fixings suited to the wall, and where the pointing is too far gone we deal with the joint first.
The pipe should also sit a short distance off the wall so air can pass behind it and the brickwork can dry. A pipe pressed flat against the wall holds moisture and can leave a damp stripe in the masonry behind.
Why does my downpipe wobble?
Usually because one or more fixings have loosened. Do not lean a ladder on it. A wobbling pipe is easy to replace the fixings on, but a pipe that has pulled apart at a joint needs more.
Should downpipes line up with the gutter bracket spacing?
Not directly. Gutter brackets and pipe clips do different jobs. The key is that the outlet in the gutter sits directly over the pipe, so water drops straight in.
What happens at the bottom: gullies, drains and water butts
The last metre decides whether the system works. A downpipe should discharge over a gully or into a drain connection set at the right height, so water leaves the pipe cleanly without splashing back onto the wall. If the pipe discharges onto a path or the ground, rain pools at the foot of the wall, soaks the footings, and splashes mud and dirt onto the lower courses of brick.
Gullies fill with leaf litter, silt and moss. A clogged gully backs water up the pipe until it overflows at the first joint it finds. A shoe that has dropped below the gully grate, or points away from it, sends water in the wrong direction. Fixing the shoe and cleaning the gully is a quick job and cures many problems that look like roof faults.
Where the rainwater goes below ground depends on the house. Many properties send roof water to a surface water drain or a soakaway, and some older houses share a combined drain with foul water. Any change to drainage connections is best checked with your water company or building control body beforehand, and we do not alter the drain itself without that discussion.
A water butt on a downpipe takes some of the flow for the garden. It needs an overflow back to the drain, otherwise the downpipe backs up when the butt is full. Our answer on fitting a water butt to a downpipe covers the details.
Why is there a damp patch at the bottom of the wall?
Check the gully, the shoe and the pointing first. Splashing water, or a leaking joint low on the pipe, is often to blame, not rising damp.
When to repair and when to replace
One damaged section can come out and a new piece go in, leaving the rest alone. A cracked length, a lost shoe or a broken clip is a modest job, and a pipe with a single split does not call for a new system. We favour whichever job properly cures the fault and no larger.
Replacement of the whole run makes sense when the pipe has gone brittle and cracks every time it is touched, when the colour has faded unevenly across several lengths, when the pipe is full of old repairs, or when the offset or fixings are wrong and the system never drains well. If the gutters are being replaced, the downpipes usually go at the same time, because new outlets rarely line up with old pipes and the finish should match.
Replacing with a pipe of a different size can change how much the system carries. Standard plastic pipe comes in round, square and rectangular sections, and matching the bore matters where the gutter has been sized to suit. Our survey notes record the existing size, so the new pipe matches.
Can I just paint an old plastic downpipe?
Sometimes, with the right primer. It can improve a faded pipe, though a pipe that is brittle or cracked needs replacing, not painting.
What does replacement cost?
MyBuilder's cost page for gutters, fascias and soffits (updated 21/08/2026) gives £30 to £70 per metre for guttering replacement overall. Downpipe pricing depends on the height, the material, the number of offsets and how easily the scaffold or ladder can reach it. A written quote follows our survey, with photographs of the pipes concerned.
Matching the roofline
Downpipes are the part of the roofline that stands out most from the street, because they run down the front wall. Colour and profile matter. Black, white, grey and brown are the most common finishes, and mixing them on one elevation shows. Our guide to black roofline looks at the dark finish, which is popular on both new and older houses.
On a house with timber fascias and bargeboards, a downpipe that matches the paint colour looks tidy. The eaves detail above also affects how the downpipe sits. A deep overhang needs a bigger offset, while a tight eaves detail may allow a plain bracket.
If you are changing the roofline, check the whole elevation together. The guide to bargeboards shows how the gable end ties in, and our page on soffit vents and loft ventilation explains why the eaves need air movement when the soffit is replaced.
Once the job is done, rubbish goes off site with us, and a written 10-year workmanship guarantee covers the work.