This DIY guide explains how to replace a shower arm. It involves five steps: First, turn off the water supply to the shower to prevent leaks. Second, remove the old shower arm and showerhead, using penetrating oil if necessary to loosen them. Third, prepare the new shower arm by cleaning the threads and wrapping Teflon tape around them for a watertight seal. Fourth, install the new shower arm by screwing it onto the pipe fitting and tightening it with a wrench. Fifth, test for leaks by turning the water back on slowly and checking all connections and if needed, re-wrap the threads with Teflon tape.