A downpipe is any pipe for carrying waste water or rainwater and fixed to a building.
Downpipes were traditionally constructed of cast iron or lead, but more recently plastic, steel and aluminium have become widely used. Downpipes may be circular or square in cross-section.
Downpipes carrying rainwater from roofs are usually fixed to the exterior walls of a building. Those carrying waste water and sewage are now fitted inside buildings, but in older homes they are attached to the exterior.
On older properties downpipes generally discharged water into a drain or gully by means of a ‘shoe’ fitted at the base of the pipe to change the direction of the flow of water, discharging it clear of the wall. In newer homes the downpipe is taken down into the ground to a direct connection with the sewer pipe, avoiding having open drains around a building.
On period properties downpipes are often topped by funnel-shaped hoppers, which collect water from one or more smaller downpipes. Elaborately-shaped cast iron and lead hoppers are of great significance on the facades of many historical buildings.
- Broken pipe – this is most likely to occur in cast iron pipes which are quite brittle, and susceptible to damage if hit. Breakages can also occur when water in a pipe freezes.
- Corrosion – cast iron pipes require regular re-painting – if this has not been carried out then rust will build up
- Loose fixing brackets – if brackets become loose, pipes may buckle, come apart at pipe joints or fall of the wall.
- Blocked pipes and hoppers
Water flowing from a cracked or broken downpipe is likely to cause damage to adjacent walls as well as causing damp problems, especially in houses with solid walls. If a pipe carries waste water or sewage then a leaking pipe will be a health risk. Broken pipes should therefore be repaired as soon as possible.
Downpipes carrying rainwater from gutters are prone to blockage from leaves and other debris. If this occurs rainwater is likely to overflow, particularly during a storm, and run down the walls of a building, giving rise to high levels of damp.
A survey report will highlight any problems and recommend any necessary remedial work.
If downpipes and hoppers on a period property need replacing it is likely that the local authority will require replacement pipes to match the original ones, especially if the property is a listed building or in a conservation area. There are a number of manufacturers who provide period-style fittings, but the cost is considerably higher than for modern plastic pipes.