Before beginning any work, gather all the necessary tools and your new replacement bathtub spout. Ensure the new spout is the correct type (or a universal model) for your plumbing. Closing the bathtub drain with a stopper or covering it with a rag is a crucial first step to prevent any small parts like set screws from being lost down the drain.

To determine the correct removal procedure, you must first identify your spout type. Inspect the underside of the spout, right against the wall. Look for a small hole. You may need a flashlight to see clearly. If you see a small screw (usually a hex screw) inside this hole, you have a 'slip-on' spout. If there is no hole and no screw, the spout is a 'thread-on' type, which simply unscrews from the pipe.

First, use a utility knife to carefully cut any caulk or sealant between the spout and the tub surround. For a SLIP-ON spout: Use the appropriate size hex key (Allen wrench) to turn the set screw on the underside counter-clockwise. You only need to loosen it a few turns; do not remove it completely. Once loose, grasp the spout firmly and pull it straight off the copper pipe. You may need to wiggle it slightly. For a THREAD-ON spout: Grasp the spout firmly with both hands and turn it counter-clockwise. If it's too tight, you can insert the handles of a pair of pliers or the handle of a wrench into the spout's opening for leverage. For very stubborn spouts, wrap the spout with a rag and use a pipe wrench to turn it counter-clockwise.

Once the old spout is removed, inspect the pipe stub-out. Use the utility knife or a putty knife to scrape away any remaining old caulk, plumber's putty, or sealant from the wall surface. Use a rag to wipe the pipe clean of any debris or mineral deposits. For copper pipe, you can use a piece of emery cloth or fine-grit sandpaper to lightly sand the exterior, ensuring a smooth surface for the new spout to seal against.

For a THREAD-ON spout: Wrap the male threads on the pipe adapter with 2-3 layers of Teflon tape in a clockwise direction (the same direction you will tighten the spout). This helps create a watertight seal. Screw the new spout onto the pipe by hand until it is snug and pointing straight down. If it's not tight enough, use a wrench (with a rag to protect the finish) to give it another quarter to half turn. Do not overtighten. For a SLIP-ON spout: Simply slide the new spout over the copper pipe until its base is flush against the wall. Ensure the set screw hole is facing down. Use the hex key to tighten the set screw clockwise until it is securely fastened. Do not overtighten, as this can crush the copper pipe.

Turn on the water and observe the spout. Check for any drips from the spout's opening. Pull up the diverter knob to send water to the showerhead and carefully check for any leaks around the base of the spout where it meets the wall. If there are no leaks, proceed to the final step. Apply a thin, neat bead of kitchen and bath silicone caulk around the top and sides of the spout where it meets the wall. Leave the bottom edge uncaulked to allow any water that gets behind the spout to drain out. Smooth the bead with a wet finger or a caulk finishing tool.