First, locate your property's water meter. Follow the path leading away from the meter towards your house. The pipe will either lead inside, possibly underground to through your foundation or lead to a large metal or plastic box attached to the pipe near ground level with small handles or spigots protruding from it.
How to Shut off Your Water Main
When to shut off the water to your house:
If you suspect a water leak anywhere in your home, turn off the main water supply. If you do not know where the leak is, turn off the main supply to prevent further water damage requiring large clean-up costs and possibly more extensive repairs. Water damage from a water leak can be even more costly than the leak itself. Water can damage your foundation, drywall, and carpeting. It can also lead to mold growth which can cause respiratory problems for family members especially small children and older people.
If you are doing major plumbing repairs, such as repiping a section of your home or placing an addition that requires additional piping, shutting the main water valve can prevent any chance of flooding. For many minor repairs, however, there are local shut-off valves, such as at your toilet or under your sink.
To shut off the water to your house, you will either turn the wheel or rotate the lever on your shut-off valve. Follow this up by opening your faucets and shower to drain the pipes of any remaining water.