Simply speaking, a belly in a pipe is a place where it sags downwards for a short time, leaving a dip in the pipe. Usually a sewer or drain will be laid on a slight downward angle, with a smooth even base, so that gravity helps the flow. If the drain has a sag in it, water will pool in the bottom rather than flowing freely. Sediment can then build up in this low point, which could then lead to a blockage. Waste will be sitting for a long period of time in stagnant water, something you definitely don’t want backing up into your home! The standing water can also lead to corrosion and decay, causing leaks.
There are many reasons why a bellied drain may form. Often it’s because the pipes were not installed correctly, either being laid at the wrong angle, using the wrong materials, or because the ground under the pipe was not compacted properly. But there are many other causes, including soil erosion, the actions of tree roots, or the effects on the soil of drought, rain, or extreme temperature fluctuations. Earthquakes too… but luckily we don’t have many of those around here!
Most of the time this bellying will occur at a joint in the pipe rather than in the mid-section. But whatever the cause, a bellied drain is a serious issue and definitely one for the professionals to tackle.
To identify if a drain is bellied, we would use CCTV to survey the pipework. Once it has been confirmed as a bellied drain, there are a few different options for fixing the pipework. This could be mean digging an open trench to access the affected part of the pipe, although sometimes it is possible to undertake a trenchless sewer repair. If you’re concerned that a drain on your property may have “pipe belly”, give us a call at Happy Drains on 0800 849 8099!