Which statement best describes a practical approach to integrating PRV and cross-connection protection in a tall building's cold water design?

• A. Install a PRV on the service line with the DCV placed to protect cross-connections, and use hydraulic calculations for sizing.
• B. Install PRV after every fixture.
• C. Do not install any cross-connection protection.
• D. Install DCV without PRV.

Answer: (B)

In tall buildings, keeping pressure under control at each outlet while preventing backflow through any cross-connection is crucial. Placing a pressure-reducing device after every fixture provides a consistent, reduced downstream pressure at each point of use, regardless of how high the fixture is in the building. This localized pressure control minimizes the driving force that could push contaminants back through a cross-connection and makes protection more reliable across all floors. It also simplifies maintenance and ensures that each outlet is independently protected, rather than depending on a single central device that would have to serve an extensive and variable network.

The other approaches are less practical here: relying on a PRV only on the service line with a DCV elsewhere adds complexity in sizing and coordination and may not guarantee uniform protection across all outlets. Not installing any cross-connection protection is unsafe, and installing a DCV without any PRV can leave the system vulnerable to pressure fluctuations that still challenge cross-connection protection.