One of the most common complaints with high-rise drainage systems is the noise of the drainage pipework, both in residential buildings with a high density of people, and in premium hotels that strive to meet customer expectations for peace and quiet.
A building is interconnected by the branch and stack pipes. If a speaker were to be placed onto the pipe it would be heard throughout the entire building through the pipe network. Sound is a sinusoidal wave travelling in the pipework at the acoustic velocity of 320m/s. In a 50-storey building the sound would travel from the base to the top of the stack in under 0.5 seconds. The sound would be subject to frictional losses and its amplitude would reduce but it would still be heard throughout the stack.
Waste water will travel down the stack between 3-6 m/s, elements containing solids such as macerated toilet paper and faeces will fall at 8-10 m/s, with solids falling at 15 m/s. The solids will fall in the centre of the stack and the macerated waste will fall both in the centre of the pipe and on the side of the pipe. Water will be annular and stick to the pipe walls.