How to Repair a Leaking Copper Pipe

Cut out the old pipe and solder in a new coupling

Photo 1: Cut out the damaged pipe

Shut off the main water supply valve, drain the damaged water line and use a pipe cutter to cut out a section of pipe that extends about 1 in. to each side of the leak. Start by gripping the pipe firmly in the cutter’s jaws and tightening the cutter’s screw. Rotate the cutter in the direction shown—as you tighten the screw handle—until the pipe snaps.

Photo 2: Clean and flux mating surfaces

Clean corrosion from the inside of the repair sleeve using a wire fitting brush. Clean the outside of the pipe with plumber’s sandcloth or emery paper. Brush flux onto all four cleaned surfaces.

Photo 3: Slide on the repair sleeve

Slide an end of the sleeve first over one pipe and then slip it back over onto the other. You may have to loosen nearby pipe hangers. Center the sleeve over the pipe ends so that about ½ in. of each pipe is inside the sleeve.

Photo 4: Solder the joint

Hold the tip of the torch flame to one side of the joint and hold the tip of the solder wire to the opposite side. Pull the solder away when enough of it melts to completely fill the joint.

When a copper water pipe corrodes and leaks, or bursts from freezing, you have to fix it fast. If the leak is pinhole-sized and less than ½ in. of pipe must be removed, you can make the repair by cutting the pipe and soldering (“sweating”) on an ordinary pipe coupling.

But to repair longer sections, use a “sweat” coupling, which you can find at home centers and well-stocked hardware stores. You can buy a sweat coupling sized to repair ½-in. or ¾-in. copper pipe. Mark the leak, shut off the main water valve and drain (or thaw and drain) the affected pipe. Cut out the damaged section (Photo 1), then measure the gap and, from the sweat coupling, cut a repair piece that’s 1 in. longer than the damaged section.

The key to a good solder joint is to keep the inside of the pipes dry, so keep a cotton rag stuffed in each pipe end to absorb dribbles of water until just before you solder. Open a faucet above that level to keep pressure from building up and dribbling more water into your repair. Then complete the steps shown in Photos 2 – 4 for a leak-proof repair. Once finished, turn the main supply valve on and check for leaks.

Sweat coupling and tubing cutter

Cut the repair sleeve from the 12-in. repair coupling stock. Smooth the rough-cut inside edges of the sleeve by inserting the blade of the pipe cutter into the cut ends and turning the cutter until the sleeve will slide over the pipe ends without snagging. Clean the sleeve’s inside edges for soldering with a ¾-in. dia. wire fitting brush.

Required Tools for this Pipe Repair Project

Have the necessary tools for this DIY project lined up before you start—you’ll save time and frustration.

• Tube cutter

Propane torch

Required Materials for this Pipe Repair Project

Avoid last-minute shopping trips by having all your materials ready ahead of time. Here’s a list.

• Emery cloth
• Flux and brush
• Solder
• Sweat coupling

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