In order to carry out any work on the water system in your house, you will need to empty the pipework first. It may not be necessary to drain down the whole system, but at least the required section will need to be drained.
Locate and label stopcocks and valves
So that you are not caught out in an emergency, it would be as well to identify and familiarise yourself with the location and effects of all the valves and stopcocks in the house. Should you have an emergency, you will be able to quickly switch off the supply or isolate a particular section.
It can be useful to label the various controls.
In an emergency, time saved can also save damage.
Draining cold water
Taps supplied directly from the mains can be isolated simply by switching off the stopcock on the rising main. This is often located under the sink. Open the tap to release the excess water.
Draining the tank in the attic
Indirect fed items are served by water from the cistern in the attic. The water from this may be stopped by closing the valve from the cistern to the section you are concerned with. Alternatively, supply from the cistern can be stopped totally.
To do this, place a length of wood over the tank and tie the ball valve up to it in the closed position. The tank can now be emptied by opening all the cold taps supplied from it.
Switching off the rising main
The same effect can be achieved by switching off the rising main and opening the cold taps. This removes the necessity to tie up the ball valve but has the downside of also cutting off supply to the direct fed parts of the system as well.