When is it necessary to use pressure-reducing valves in a plumbing system?

Pressure-reducing valves are essential in plumbing systems primarily to protect the infrastructure from high pressure. The correct situation for their use arises when the supply pressure exceeds 80 psi. High water pressure can lead to various issues, including leaks, bursts in pipes, and excessive wear on fixtures and appliances. By employing a pressure-reducing valve, the downstream pressure is lowered to a more manageable level, typically around 50 to 60 psi, which minimizes the risk of damage and optimizes the functioning of the system.

The other options do not accurately determine the necessity of pressure-reducing valves. While a supply pressure exceeding 60 psi may raise concerns, the standard threshold for implementing such valves is at 80 psi. The number of fixtures in a system and the type of piping material, like PVC, do not directly dictate the requirement for pressure-reducing valves. Thus, recognizing the specific pressure guidelines helps ensure a safer and more efficient plumbing system.