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Clearing a blocked stack

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The two pipe system can sometimes cause problems. There are clearing eyes at direction changes and junctions in the waste stack, but the covers can often prove difficult to remove. Use oil to soak the cover, particularly the bolts before removing the cover. Insert a rod in the direction of the blockage. Rinse water through the system to flush any debris away before re-sealing. Before replacing the cover smear a little grease around the frame to stop any rust in the future.

If the problem arises in the soil stack, the job is more difficult and unpleasant to tackle. Look for the clearing eyes. Attempt to open the cover or access plug. To unblock soil stacks an auger should be hired to use. An auger is a flexible coiled wire which will pass through small diameter wastepipes to clear a blockage. The corkscrew head is passed into the wastepipe through the opening in the direction of the blockage. When the obstruction is found, the cranked handle at the other end is clamped and turned. Next either push or pull the rotating head when the blockage is engaged and then dislodge. Rinse water through the system to flush any debris away - a hose is usually helpful at this stage.

Cleanse the area carefully and disinfect the surrounding system thoroughly once the cover has been replaced. If the clearing eyes prove impossible to remove, particularly in an older property where the pipe is made of cast iron - call in a professional cleaning company. This is because it will probably have to be accessed and unblocked via the vent above the roof.


The hopper is a collection point for water from indoor appliances. It is normally installed at first floor level on an outside wall and linked to a downpipe leading to a gully. If the hopper stack is blocked, it can usually be cleared by hand - protective gloves are advisable. Remove the debris from the hopper then use a rod or stick to gently plunge the drainpipe. Use a wire coathanger to clear the bottom end of the pipe. Cleanse and disinfect the inside of the hopper and flush the pipe.

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