It is not uncommon for soil stacks and drain gullies to become blocked. Soil stacks can become blocked at any time, but gullies are more prone to get blocked during autumn and winter. In most cases, clearing stacks and gullies is a fairly straightforward job providing you follow a few simple guidelines.
Clearing a Soil Stack
If you notice that several of the outlets in your home are draining slowly (bath, sinks, etc) then it is probable that the soil stack is blocked or partially blocked. If the stack is not cleared, you will not only notice a smell (particularly in hot weather) but you might also find that waste water is back up into the house. To clear a soil stack, you will need to buy or hire a flexible drain auger.
Modern plastic soil stacks will have a hinged or pressure fit access plug, usually close to where the branch pipes join the main stack. This can be removed to allow access to the inside of the stack. As you won’t know where the blockage is in the pipe, be prepared for waste water and possibly sewage to spill out when you remove the access plug. Wear gloves and goggles to prevent contamination of your eyes and hands.
Remove the plug and let any waste water drain out. If there is a lot of waste water in the pipe, the blockage is probably below the access plug. Feed the auger into the soil stack until you reach the blockage. Turning the handle on the auger should then break up and remove the obstruction. You may need to push and pull the auger in and out to completely break up a very compacted blockage. With the obstruction cleared, hose out the stack and replace the access plug. You should not carefully hose down and disinfect the area around the pipe where waste water was spilled. Also be careful to wash your hands and any clothing which might have been splashed with sewage.
Cast Iron Soil Stack – If you have a Cast Iron soil stack it is worth thinking about getting a specialist cleaning company in to unblock it. Cast iron stacks generally do not have an access point so it will need to be unblocked via the vent above the roof.
Unblocking a Gully
Gullies, the drains at the bottom of your downpipes, will often get blocked by leaves and other garden debris over the autumn and winter. If the grate is cleared off regularly, a blockage should not be able to form very quickly, but a gradual build up of dirt and debris can still eventually stop the gully working as it should.
Using an Auger
Remove the grate and insert the auger into the gully until you reach the blockage. Rotate the handle on the auger to break up the obstruction and get the water flowing. Once the majority of the debris has been cleared, hose out the gully and pour a little disinfectant down it to kill bacteria. Clean and replace the grate to finish off.
If you do not have an auger, you will need to clear the gully by hand. Wearing rubber gloves, use a small container to scoop out as much of the standing water as possible. You will then need to reach down into the gully and remove the blockage by hand. When you have removed most of the debris and the water starts to drain away, you can use a hose to clear the rest. Disinfect the area, then clean the grate and replace it.