Leaks in copper pipes can be troublesome. To repair a water line with copper fittings, you have to have reasonable soldering skills or your repair may not be watertight. Even if you have the skills, though, soldering isn’t easy if you can’t completely turn off the water. The solution is to adapt the line to PVC plastic. You have to connect adapters to the copper line, which involves a minimal amount of soldering, but you can make the final connections by gluing PVC, which is a much less difficult — almost foolproof — way to seal the line.
Turn off the valve that controls the damaged copper water line.
Cut out the damaged section with a pipe cutter. Make two cuts in the pipe and remove a section that has a minimum length of 8 to 10 inches, even if the leak is very small. Place a bucket under the line and let the water drain out.
Clean the ends of the copper pipes with a wire brush to remove oxidation, grease and oil. Spread soldering flux on the ends of the pipes and on the insides of the slip connections of two copper male adapters that are the same size as the pipe. Slide the adapters onto the ends of the pipes.
Heat the adapters with the torch until the flux begins to smoke, and then apply lead-free solder to the joints, moving the tip of the solder wire around the joint so that it melts and fills all the gaps between the pipe and the fitting. Let the pipes cool for about 10 minutes.
Wrap plumbing tape around the threads of the adapters, screw a PVC female-to-slip adapter onto each one and tighten it with a wrench. Don't over-tighten, or you may crack the plastic.
Measure the distance from the end of one plastic adapter to the end of the other with a tape measure and add 1 inch to the measurement. Cut a length of plastic pipe of the same diameter as the copper pipe you are repairing to this length, using a hacksaw.
Deburr the ends of the pipe with a file. Spread PVC cement on one end and on the inside of one fitting, and then quickly insert the end into the fitting and give the pipe a quarter-turn. Hold it in place for a three-count to allow the cement to set.
Spread glue on the other end of the pipe and on the inside of the second fitting. Pull the pipes toward you until the end of the pipe clears the fitting, and then insert it and release the pipes. The end of the pipe should slide into the fitting, but you may have to guide it or give it a little push. The glue will set quickly to complete the repair.