Rainwater leaves a roof in stages. The gutter collects it and carries it to an outlet. A vertical pipe, the downpipe, drops it down the wall. At the bottom it enters a gully or a shoe and goes to a drain, a soakaway or a water butt. Every stage has to work, and a fault anywhere sends water into the wall, the foundations or the neighbouring ground instead.
This guide looks at the whole downpipe system: the parts, how they are connected, the faults that come with age, and the point at which a pipe should be replaced. It treats the system as a whole. When a single pipe refuses to drain, our step by step answer on a blocked downpipe is the place to start. The service itself is described at guttering, soffits and fascias.
The parts of a downpipe system
Even a simple house has more fittings than the straight pipe suggests. Knowing the names helps when you describe a fault or read a quote.
From outlet to ground
The gutter drains through an outlet, a hole in its base or end, into the top of the downpipe. Where the pipe has to step in or out to clear a projecting eaves, a swan neck (two bends forming a short offset) carries it round the overhang. Brackets or clips hold the pipe off the wall and fix it at intervals; lugs on the pipe sockets stop it sliding. Each length slots into the one below, and the joints are made in the direction of the flow, so water running down does not escape through the socket.
Hoppers
A hopper is an open box at the head of a downpipe. It takes the flow from a gutter, or from a bath or basin waste, and funnels it into the pipe. Cast iron hoppers are common on Victorian and Edwardian houses, and plastic ones on later buildings. A hopper that is blocked or cracked overflows into the wall behind it.
The foot
At ground level the pipe ends in a shoe, which kicks the water out over a gully or a channel, or it feeds directly into a rainwater gully, a trapped drain inlet with a grating. Some older houses have a back inlet gully, where the pipe and the gully grating meet at a cast fitting; these are prone to silting and need to be rodded out from time to time. Where there is a rainwater harvesting system or a water butt, a diverter takes some of the flow before it reaches the gully.
Materials and what they do with age
The pipe is usually the same material as the gutter, because the fittings come as a system. The choices behave differently over time.
Plastic
Most modern downpipes are uPVC. Light, quick to fit and available in round, square and rectangular sections, they suit most houses. They can become brittle after many years of sun and frost, and a knock from a ladder or a ball can crack them. Pureseal Services, a cleaning firm, gives uPVC rainwater goods a life of 10 to 20 years in a December 2025 article; it is a single low-confidence source.
Cast iron and aluminium
Cast iron pipes are heavy and last, but rust from the inside when water sits in them and split in a hard frost if blocked. Cast aluminium is lighter, does not rust and comes in profiles that follow the iron originals. The same source gives aluminium 20 to 30 years and cast iron 40 to 70, sometimes more. Our gutter materials guide compares the three on cost and appearance.
Asbestos cement
Some buildings from the mid twentieth century have asbestos cement downpipes, which look like a dull grey, slightly rough tube. HSE guidance lists asbestos cement rainwater goods among non-licensed work when taken off carefully and not broken up; substantial breakage is treated differently. If you suspect it, do not drill, cut or scrub it, and tell us before work starts.
Whichever material you have, the best protection is the same: keep the water moving, and keep the pipe fixed firmly to a sound wall.
Where the water goes at the bottom
What happens to rainwater at the foot of the pipe depends on the property. It may go to a surface water sewer, to a combined sewer shared with foul water, to a soakaway in the garden, or to a water butt that overflows to one of these. Your drainage layout tells you which; ask your water company or building control if you are unsure, because it affects what you can change.
Gullies and silting
A gully traps silt and stops drain smells rising. Between storms the grating collects leaves and moss, and silt slowly builds up in the trap. If a gully fills, water backs up the downpipe and overflows at the first weak joint or the hopper. Lifting the grating and scooping out the sludge is a routine job, and we do it on visits where the pipes are in question.
Soakaways and slopes
On a sloping plot, which describes many gardens around Stroud, a pipe that discharges to the surface sends water downhill towards the house wall or the neighbour's boundary. Where a downpipe ends over a path, the surface should carry water away from the building, not along its base. So the survey follows the water beyond the pipe, to wherever it finally lands.
Connections and consent
Changes to how a house drains, such as connecting to a different drain or adding a new soakaway, are a matter for building control and the water company. Swapping a like-for-like downpipe over an existing gully is not. If you plan a change of discharge, check with your building control body first.
How downpipes fail
Faults tend to appear at the same few places, and a walk around the house in the rain shows most of them.
Blockages
Leaves, moss and silt sink to the bottom of a pipe, and a bend is where they stick. A pipe that is dry at the shoe when the gutter is full, or one that gurgles and overflows at the hopper, is blocked. The first step is to clear it; the cause is often a build-up that began in the gutter, so our gutter cleaning guide deals with the first link in the chain.
Leaking sockets
Where a pipe has lost its fall in the bracket or its joints have pulled apart, water escapes at the socket and runs down the wall. A green or black stripe beneath a joint is the giveaway. A leaking pipe in a cavity wall is a particular worry, because the water soaks in unseen.
Cracks and splits
Frost splits plastic and iron pipes along a seam, usually where water has stood after a blockage. A knock splits an old plastic pipe cleanly. A crack that is only a hairline in dry weather can leak freely in a downpour.
Loose or missing brackets
A pipe that leans away from the wall has lost its brackets, or the plugs behind them have failed. Wobbling pipes loosen further each storm, and a pipe that has dropped out of its shoe discharges against the wall.
Overflow from the head
When the head of the pipe is too small for the gutter above it, water spills over the hopper in heavy rain even when nothing is blocked. That is a design problem, and the cure is a larger outlet or a second pipe.
When to replace rather than repair
Many downpipe faults are repairs. A blocked pipe is cleared, a loose bracket is refixed, and a cracked section is cut out and replaced. A repair makes sense when the pipe is basically sound and the fault is local.
Signs it is time for a new pipe
A pipe is better replaced when it has several failures at once: cracks near the head and the foot, joints that have opened, brittle plastic that snaps when touched, or iron that is flaking away inside. Repeated blockages in the same bend can point to a pipe that is the wrong size for its work. And where a pipe has been fixed to a wall in a poor position, such as running behind a bush or across a window, replacement is a chance to move it.
Matching what is there
On older houses, matching matters. Pattern and material can be fixed by a listing or by a conservation area, and the council's conservation officers will tell you what applies before you order anything. A cast iron pipe with a decorative hopper head is part of the building's character as much as its windows.
What it costs
Published guides usually price the roofline as a whole. MyBuilder's 2026 price guide gives guttering at £30 to £70 per metre and scaffold at £20 to £40 per m². Downpipes are usually priced with the rest of the gutter run, and their cost depends on the material, the length and the height of the wall. Following the survey, the written quote sets out the work on the pipe, brackets, fittings, access, any gully work and clearing away.
Access on steep plots and in tight lanes
Many houses around Stroud sit on a slope, with a narrow path at the foot of the wall or a steep drop at the back. Downpipes on those walls are harder to reach than they look. A ladder footed on a path that falls away is unsafe, and a scaffold may have to stand on a stepped base.
Planning the work
We look at the access at the survey. If the pipe can be reached from a short tower or a podium step, that is how the job is done. If the wall is tall, awkward or shared with a neighbour, a scaffold is planned and priced from the start, rather than found out on the day. Where a drop is long, a pipe can be replaced in lengths from the top down, so no joint is left loose between visits.
Neighbours and shared walls
In terraces and pairs of semis, one downpipe at the party wall sometimes takes two roofs. Work on a shared pipe affects the neighbour, so we tell you early who will need to be told, and what they will see.
Other roofline timber
While the access is up, the fascia, the soffit and any bargeboards on the gable are in reach. A soft board or damp soffit behind a leaking hopper is common. Our guide to soffit ventilation explains why the soffit vents need to stay clear, and the guide to bargeboards covers the gable timbers.
What the work involves and what you get
A downpipe job starts with a look at the whole line, from the gutter outlet to the drain. We check the gutter above, the hopper, the bends and brackets, the shoe and the gully, and we run water through to see where it goes. Your own pipework is photographed, fault by fault, for the survey notes.
The quote and the work
Our written quote follows the survey and covers what comes off, what goes on, brackets and fixings, any repair to wall or timber, access and waste. Pipes are fitted from the top, each socket seated in the direction of flow, with brackets at fixed points and the foot set over the gully. We run water through at the end to check it.
Our 10-year workmanship guarantee is written down, the old pipe is removed and the ground is left tidy.
What to send first
To find out whether yours is a repair or a new pipe, send a photograph of the head of the pipe, the foot and any stain on the wall, and say whether the pipe overflows, drips or just looks tired.