Step 1 · Shut Off Main Water and Prepare Work Area
The first and most critical step is to prevent any water flow to your work area. Locate the main water shutoff valve for your entire house. This is often found in a basement, crawl space, or utility closet near where the water service line enters the home. Turn the handle or lever clockwise until it stops to completely shut off the water. Next, relieve pressure in the plumbing system by opening a faucet on the lowest level of your home (like a basement sink or outdoor spigot) and letting it run until the water stops. Back at your work area, place a small bucket directly under the angle stop you are replacing and lay down several old towels to catch any residual water that will spill out during the process. Finally, gather all the tools and your new angle stop so they are within arm's reach.