Repairing a leaky copper water pipe elbow generally involves removing and replacing the leaky elbow fitting. For one reason or another, the solder surrounding the existing elbow fitting may have failed beginning with a small leak. Small leaks over the period of days or weeks can grow. Copper pipe fittings are soldered into place; the existing solder is remelted in order to remove the existing elbow fitting. A new fitting must be soldered into place in order to make the joint leak resistant again. Only the correct tools are needed to complete this project---not an expensive licensed plumber.
Turn the water off to the leaky copper water pipe elbow. Allow the water to drain away from the elbow joint by turning a water faucet on that is below the leaky joint in elevation.
Wipe residual water away from the leaky joint so the copper pipe is dry. Light a BernzOmatic torch and place the flame directly onto the leaky joint.
Allow the joint to heat up for a few minutes. When the solder melts and liquefies, pull the elbow fitting away from the ends of the copper pipes that help create the joint. While the copper pipe is still hot, wipe the excess solder away with a damp cloth rag. Remove excess solder from the elbow fitting as well.
Inspect the condition of the elbow fitting. If it is damaged, out of round, or nicked, scraped, or otherwise unfit for reinstallation, replace it with a new elbow fitting.
Brush flux paste onto the ends of the two copper pipes. Apply a little flux paste to the inside of the elbow fitting.
Place a new copper fitting over the ends of the two pipes. Reapply the flame from the BernzOmatic torch to the copper pipe and fitting for a few minutes, or until the copper is hot enough to melt solder on contact. Touch the end of a piece of solder directly to each joint running solder around the whole joint on both copper pipes.
Allow the pipes and the solder to cool for a few minutes. Turn the water to the elbow joint back on to finish cooling the pipe and to test the quality of the new joint.
If the joint still leaks after it is fixed, the ends of the copper pipes may need to be replaces with new pieces of pipe.