What is the recommended procedure for flushing a new cold water system prior to first use?

• A. Open outlets gradually starting from the furthest points
• B. Open outlets gradually starting from the nearest points
• C. Open all outlets at once
• D. Flush only the mains

Answer: (A)

When commissioning a new cold water system, you want to clear air and any debris from the piping and bring fresh water through every run. Opening outlets gradually from the furthest points ensures water is pushed through every section of the system, forcing air and sediment out toward the mains and out of the farthest outlets first. This method also helps avoid sudden pressure surges or water hammer that can occur if many outlets are opened at once. As the farthest taps run clean, continue opening progressively closer outlets until all outlets have been flushed. Opening only the mains wouldn’t clear the branch lines and fixtures, leaving dead legs and potential debris in the system.