What is the function of a pressure-reducing valve in plumbing?

A pressure-reducing valve is designed specifically to lower incoming water pressure to a manageable level for plumbing systems. High incoming water pressure can potentially cause damage to pipes and fixtures, leading to leaks or mechanical failures. By installing a pressure-reducing valve, the pressure is regulated, ensuring that it is at a safe level for use throughout the plumbing system.

This is particularly important in residential and commercial buildings where the municipal water supply can sometimes exert excessively high pressure. The valve works by actively adjusting the flow of water coming into the system, allowing only a specific maximum pressure to pass through, which is crucial for protecting plumbing systems from the detrimental effects of high pressure.

Other options do not describe the function of a pressure-reducing valve. Maintaining high pressure is counter to its purpose, preventing leaks is a separate issue typically handled by good installation and maintenance practices, and filtering impurities relates to water quality treatment rather than pressure regulation. Thus, option B accurately reflects the essential role of a pressure-reducing valve in plumbing.