Isolation valves (Ballofix) are used to cut off the water supply to a water source. This includes washing machines, dishwashers, taps, baths, toilets etc + only cost around £1 each!
They should be installed to every water source as it makes it easier for any maintenance/ repair work. When there is no isolation valve you have to search for the Stop Tap and hope that it is operational. This is the last thing you want to do when there is a major water leak!
Isolation vales come with a screw to open and close them, some of them come with a lever.
This isolation valve is turned off as the screw head is horizontal.
This Isolation valve is turned on as the screw head vertical.
They come in compression fittings or push fit which makes it easier to fit. Push fit are usually more expensive due to the speed of installation.