There is a difference between Waste Pipes and Soil Pipes
The water that flows through waste pipes is sometimes called “grey water.” This would be water from a sink, a shower, a washing machine, or a bath that would be sent to a soil and waste stack.
Soiled water which uses soil pipes is usually from the toilet. The waste passes through soil pipes, then into the stack, and then into the sewer.
There are several reasons why we may need to be called out for waste or soil pipes. Replacing an old toilet that has gone out of style or developed a fault, leaks under the sink or bath, alternatively, you may have moved into a house without a toilet in the bathroom at all, and need to start from scratch having one installed.