There are 3 easy steps to turning off your water in an emergency: Find your valve, turn it off, and open a garden faucet. It is important that you leave the garden faucet open since not all valves work perfectly. Leaving this open provides an escape for any remaining water pressure!
Find Your Valve
Your valve is usually located on the same side of your house as the city meter. Most often there will be a garden spigot right near the valve.
A Note Regarding Water Meters
In the event of emergencies, you may be able to turn off the water at the meter itself. Many municipalities have restrictions on turning the valve, so make sure you are aware of your local codes. You may need to call the water provider and wait several hours for an employee to come turn your water off. In some cities, you may even be subject to fines, and liable for replacement were the valve to break, potentially several thousand dollars. In that case, consider your costs. A dripping faucet is not a major concern, but a broken pipe flooding your home could cost you tens of thousands to repair all the damage that occurs.