Soil pipes stabilize the pressure in a drain. Without this, the water from a U-bend can be sucked away, leaving a home exposed to noxious odours. There is also the risk of water being pushed up the U-bend and the toilets in a home being flooded.
There’s no need to worry about such unpleasant things, however, when you eliminate the risk with a Klober Uni-Line Soil Flexipipe.