Downpipe blocked? How to get the water flowing again

A downpipe, also called a rainwater drain or RWP, carries rainwater from the roof down to ground level. At the bottom, the water enters the sewer, an infiltration facility in the ground, or it runs into the garden or street via a spout or gully. How it works at your property depends on the construction of your home and the arrangements in your municipality. If that route becomes blocked somewhere, the water will find another way. That is not only inconvenient, it can also cause damp in façades, window frames and cellars.

How do you recognise a blocked downpipe?

• Water overflows the edge of the gutter, even though it's not raining extremely hard.
• Water is coming from a joint or seam of the downpipe, halfway up the façade.
• At the bottom near the ground, water is bubbling or gurgling from the pipe or around the connection to the sewer.
• You hear gurgling or bubbling in the pipe during a shower.
• Damp patches appear on the façade or inside against the wall, close to the downpipe.
• After rain, water remains standing in the gutter for a long time or continues dripping for hours afterwards.

What causes a downpipe to become blocked?

• Leaves and twigs. Especially in autumn and with trees nearby, leaves wash from the roof into the pipe. Wet leaves clump together into a blockage.
• Moss and roof debris. Moss and fine material wash off tiled roofs. This settles in bends and in the lower part of the pipe and sometimes hardens.
• Bird nests. Birds like to build in the opening of the downpipe or in an overflow. Twigs and feathers then form a solid blockage at the top.
• Sand and silt. Sand and gravel also wash off flat roofs. This collects in the access point or in the connection to the sewer.
• A problem in the underground pipe. If the downpipe is connected to the sewer, the blockage may also be in that underground pipe, for example due to subsidence or roots. Read more about this in sewer subsided or full of roots.

Where is the blockage? First check from ground level

You can learn a lot without climbing anywhere. During or just after a shower, watch where the water goes.

• Is the gutter overflowing, but hardly any water coming out of the pipe at the bottom? Then the blockage is probably at the top, at the gutter outlet or in the first bend.
• Is water coming out of a joint halfway up? Then the blockage is below that joint.
• Is water coming up at ground level or running away around the pipe? Then the problem is in the lower section, the access point or the pipe underground.

Many downpipes have an access point at the bottom: a section with a flap or removable cover, or a loose piece of pipe that fits into the connector to the sewer. Sometimes there is a leaf guard or leaf basket in the pipe or at the top near the gutter. This catches leaves, but must itself remain clean. A full leaf guard is one of the most common causes of an overflowing gutter.

Step-by-step plan: what you can safely do yourself

1. Wait until it's dry. Don't work during a downpour or in strong wind. Wet surfaces and water that suddenly releases make it unnecessarily risky.
2. Open the access point at the bottom. Have a bucket ready and wear gloves. Open the hatch or remove the loose bottom section from the fitting. A lot of water and debris can come out at once.
3. Remove the debris by hand. Clear leaves, sludge and sand from the access point and from the connection to the sewer, as far as you can reach.
4. Flush from the bottom upwards. Carefully flush upwards into the pipe with a garden hose and then downwards into the connection. If still nothing comes through, the blockage is higher or deeper.
5. Use a hand snake, only where you can reach safely. A short hand snake can loosen a blockage in the lower section or in the first metre of the connection. Turn gently and do not force anything.
6. Replace everything and test. Put the access point or leaf guard back and pour a bucket of water in from the top, if you can reach it safely from the ground or a window. Otherwise, check it during the next downpour.

If it does not work from ground level, or if the blockage is clearly at the top or underground, stop. Then a plumber with the right snake, jetting equipment and, if necessary, a camera is the sensible choice.

Ladders and roofs: don't take risks

Every year accidents happen with ladders when working on gutters and downpipes. A few metres is enough for serious injury. If in doubt, stay on the ground.

• Only use a sturdy ladder that is properly positioned on level, dry ground, and make sure someone holds the ladder steady.
• Do not reach far to the side; move the ladder instead.
• Never work on a wet, slippery or steep roof, or in wind or darkness.
• Keep away from electricity cables, satellite dishes and other obstacles.

Good advice: anything you cannot reach from the ground or from a safe window is best left to us.

What you'd better not do

• No chemical drain cleaner in the downpipe. It doesn't work against leaves and moss and ends up in the environment via the sewer or soil.
• Do not poke hard into the pipe with a stick or broom handle. Zinc and PVC damage easily and you often push the blockage in more firmly.
• Do not detach the pipe from the façade to get better access. Brackets and connections do not always go back properly afterwards.
• Don't ignore an overflowing gutter. Water running down the façade can cause damp inside over time. See also damp patches on the ceiling.

What PandFix does

We focus on the drainage system itself: the downpipe, the access point and the connection to the sewer or underground pipe. We clear the blockage using a rod or jetting equipment, and if it keeps recurring we can use a camera inspection to check whether the underground pipe has subsided or is damaged. If a repair is needed, you can read more on the sewer repair page. Periodic cleaning of the gutter itself is not part of our services; for that you can contact a window cleaner, roofer or specialist maintenance company.

How to prevent a blocked downpipe

• Have the gutter cleaned regularly, especially after autumn and if there are trees nearby.
• Fit a leaf guard or basket and empty it regularly.
• Occasionally open the access point at the bottom to remove sand and sludge.
• Prune branches that overhang the roof.
• Watch for signs such as gurgling or dripping after rain; early intervention is easier.

If rainwater is coming up at the bottom and drains in the garden are also not draining properly, also read about a blocked outdoor drain or see our page on drain unblocking. In The Hague or Delft? See drain unblocking in The Hague centre and drain unblocking in Delft.