Most homes use copper piping in their plumbing systems, built up from multiple sections of pipe. If you develop a leak in a copper pipe, it usually is possible to replace just the piece of pipe that is leaking and leave the sound plumbing around it intact. Soldered joints in copper plumbing may look permanent, but with some basic tools they can be disassembled and repaired relatively easily.
Turn off the water supply at the source and open all the faucets in your house. Allow the system to completely drain all the water out.
Cut out the leaking section of pipe roughly six inches from where it enters the joints at each end. Wear safety goggles and gloves to do this.
Clamp a pair of locking pliers onto the piece of pipe that is still attached to one of the joints.
Gently begin to heat the joint with a propane torch; you are aiming to heat the joint evenly and soften the solder without overheating the copper pipe. If the joint starts to discolour stop applying heat and wait until it cools before continuing heating.
Start trying to twist the pipe using the pliers as soon as you see the solder start to melt and flow; continue to apply gentle heat as you do this. Pull hard on the pipe while continuously twisting back and forth and it will eventually come free from the joint.
Wipe the remaining joint inside and out with an old rag as soon as the damaged pipe is removed. This must be done before the joint has chance to cool and the remaining solder reharden.
Repeat steps three through six to remove the other end of the damaged pipe from its joint. Use emery cloth to thoroughly clean the joints and make them ready to accept a replacement section of pipe.
Use extreme caution when using a propane torch. Always wear appropriate safety equipment while cutting and heating pipework.