The 9mm in-line tap is a handy accessory. It can be inserted in-line just outside the connection to your 30 or 47-L plastic reservoir.
This allows you to turn off the water if you need to pause supply or undertake maintenance.
Also, it can be added to the end of the layout so that now and again, you can open the tap to allow the lines to be flushed, thus removing any limescale build-up or sediment that might have occurred over time.
This only takes a few minutes and needs to be done every couple of weeks.