What is the primary cause of water hammer in a sewage system?

Water hammer is a phenomenon that occurs in fluid systems, notably in sewage systems, when there is a sudden interruption to the flow of fluid. This interruption creates a shock wave that travels through the pipe, leading to potentially damaging effects, such as loud banging noises, vibration, and even structural damage to the piping system.

The primary cause of water hammer is when the flow of sewage is halted abruptly, leading to a rapid change in pressure within the system. This can happen, for instance, if a valve is closed too quickly, causing the kinetic energy of the moving sewage to be abruptly converted into pressure waves throughout the system.

While other factors, like pumping to extreme heights or having debris in the sewage, can impact the operation of a sewage system, they do not specifically contribute to the rapid changes in pressure associated with water hammer. Similarly, excessive corrosion in the pipes may lead to weaker pipes but is not directly responsible for the wave phenomena created when flow is interrupted suddenly. Thus, the correct answer focuses on the mechanics behind water hammer being linked to the abrupt cessation of flow.