Most houses have a stop tap in the pavement outside the property. Depending on the age of the property, or if the water authorities have done some renewal work, it should be a small rectangular, or circular black cover that can be prised open with a screwdriver.
Inside should either be a stop tap, or in newer cases a plastic hexagon key which effectively does the same thing.
Simply turn the water supply off and test it by opening a tap to check no water is passing.
If you cannot find an outside stop tap then you may need to freeze the pipe below the stop cock. Freezing kits are available from most diy shops but BEWARE. You need at least 9 inches distance to the stop cock or the ice in the pipe will prevent you fitting the new stop cock PLUS you need to ensure you can make your replacement in around 10 mins or the ice will melt, and your house will get very wet as full mains pressure pushes water into your house at 20 litres a minute.
Nick from sunny Sale, March 2009
