What initial procedure is normally carried out when preparing to bring a new cold water system into operation for the first time?

• A. Flush the system out using clean water
• B. Fill the system with water and pressurize
• C. Perform a full pressure test before filling
• D. Empty the system completely

Answer: (A)

Starting a new cold water system requires ensuring the water path is clean before it ever reaches any outlets. Flushing the system with clean water does exactly that: it pushes out any debris, swarf, flux residues, or other construction residues that can have entered the pipes during installation. By running water through all sections and opening outlets, you carry contaminants to waste and can verify that water is flowing freely and that valves operate correctly. This initial cleaning reduces the risk of blockages, taste or odor issues, and contamination once the system goes live. After flushing, you typically proceed to fill and pressurize the system and perform the necessary commissioning checks.

If you skip flushing and go straight to filling or testing, debris can be pushed into fixtures or filters, potentially causing blockages or contamination, which is why flushing is the standard first step.