When should the taps be turned off when closing after installation?

Turning off the taps in the correct order is important to prevent issues such as backflow and to ensure that the plumbing system is properly sealed during the closing process. The recommended method is to start with the upper floors and then proceed to the lowest level. This approach allows the water to drain downwards naturally due to gravity, which minimizes the risk of trapped air or water in the plumbing lines.

By starting from the upper taps, any remaining water flows down into the lower pipes, reducing the pressure in the system effectively and preventing the possibility of leaks or bursts in the pipes as the water is removed. Additionally, this method helps manage air pockets that might get trapped in the system, ensuring a smoother closure and reducing the risk of damage to the plumbing.

The other options do not adhere to this gravity-driven principle and could potentially lead to complications in the system, which is why the correct sequence involves addressing the upper floors first before moving to the lower level.