It varies from home to home, but if you have a basement or crawl space, it’s typically located on an interior wall near the front of the house. In homes built on a slab, the water main valve might be located inside the garage or near the water heater. If it’s not inside the house, check near the end of your property line for a water box, which you may need a key to get into. If you still can’t locate the water main, ask your plumber for assistance. Warning: Never touch the pressure regulator or tamper with a city meter!