There is usually a water shut off tap downstairs, in modern houses these tend to be under the kitchen sink, but on older properties the location can vary. There will usually also be a mains water shut-off valve is usually located near the perimeter of your house, below the ground level, often at the front of the house, or along the street under a small cover. It is important to know where the water shut-off tap is located in case you need to quickly shut off the water supply to your house in an emergency