Step 5 · Test for Leaks
Once the soldered joints have completely cooled, reinstall the valve cartridge. Make sure the valve is in the 'off' position. Go to the main shut-off valve and turn the water back on slowly. Return to the shower and meticulously inspect every new pipe connection and solder joint for any signs of dripping or weeping water. Use a flashlight for a clear view. If a leak is found, you must shut off the water, drain the system, and re-solder the faulty joint. Once you're confident there are no leaks, turn the valve on to test both hot and cold water flow and the diverter function.