What must air/vacuum relief valves ensure during operation?

Air/vacuum relief valves play a crucial role in maintaining the proper pressure balance within a septic system's distribution pipes. These valves are designed to open and allow air to enter or escape from the system as needed, which helps prevent the formation of vacuum conditions that can disrupt liquid flow and lead to potential system failure.

When liquid waste flows through the system, changes in pressure can occur. If the pressure drops too low, it may create a vacuum that can hinder the efficient transport of waste. Conversely, excess pressure can also cause issues, leading to potential backups or leaks. Properly functioning air/vacuum relief valves ensure that the pressure remains within acceptable limits, allowing for consistent and reliable operation of the septic system.

Regular maintenance checks are essential for the health of the entire system, but they do not directly pertain to the primary function of air/vacuum relief valves. Similarly, steady or increased flow of sewage is a result of the system's design and function and is not something the relief valves directly ensure. The main focus of air/vacuum relief valves is to maintain appropriate pressure, making option B the correct choice.