Locate the main water shutoff valve
Check the basement, crawlspace, utility room, garage, or outside meter box
Turn the valve clockwise until it stops if it is a round wheel-style valve
Turn the lever handle one quarter turn until it is perpendicular to the pipe if it is a ball valve
If needed, shut off water at the street meter valve
Open a faucet inside the house to relieve pressure and drain remaining water
Turn off the water heater if the water will be off for an extended time
Confirm water is off by testing a faucet
Call a plumber or utility company if the valve is stuck or inaccessible