Which action most clearly constitutes the first step when decommissioning a cold water system?

• A. Isolate and reduce the system pressure
• B. Flush the system with clean water
• C. Recharge the storage cistern
• D. Engage a supervisor

Answer: (A)

The first priority when decommissioning a cold water system is to stop water entering and to relieve the pressure so work can be done safely. Isolating the system by closing the main supply or isolation valves prevents any further water flow, and reducing the system pressure minimizes the risk of leaks, bursts, or sudden water movement as you proceed. Flushing the system would push water through while it’s still connected, which isn’t safe before it’s isolated. Recharging the storage cistern would reintroduce pressure and isn’t necessary at the start. While involving a supervisor is important for procedures and approvals, it doesn’t by itself prepare the system for safe decommissioning. So isolating and reducing pressure is the correct first step.