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How to Connect Copper to a PVC Waste Pipe

Updated July 20, 2017

With the use of special adaptors, you can connect copper to a polyvinyl chloride (PVC) waste pipe, allowing you to repair or expand your plumbing system without the expense of a full copper installation. PVC pipe is easy to work with and it is durable and inexpensive, making it perfect for use in waste handling. A variety of PVC fittings are available, making it easy to expand a PVC pipe system later without needing to solder or invest in expensive copper.

Turn off the water supply. Open a faucet to depressurise the system. Cut the copper pipe with the hacksaw, using the bucket to catch any water remaining in the pipe. Dry the inside and outside of the copper pipe.

Sand the outside of the copper pipe with the emery cloth about 2 inches from the cut end. Sand the inside of the copper male adaptor.

Apply a thin layer of soldering flux around the sanded area of the copper pipe and on the inside of the copper male adaptor.

Slide the copper male adaptor onto the pipe. Twist it to make sure the flux is evenly distributed on both mating surfaces. Wipe off the area with a rag to remove excess flux.

Heat the circumference of the joint using the propane torch, holding the torch perpendicular to the pipe. Watch for the solder flux to heat enough to drip. Apply the solder all of the way around the joint. Allow the joint to cool naturally.

Wrap Teflon tape around the threads on the copper fitting, keeping tension on the tape so that it is pulled into the threads. Overlap each wrap by half the width of the tape and continue wrapping it until all of the threads are covered.

Tighten the PVC-threaded female adaptor onto the copper male adaptor initially by hand, and then use the pipe wrench to tighten the fittings.

Apply the PVC primer to the inside of the fitting slip joint and the outside of the PVC pipe. Stir the PVC cement according to the manufacturer's instructions. Apply the cement to the primed areas of both the fitting and the PVC pipe. Quickly slide the pipe into the fitting. Wipe away the excess cement.

Allow the joint to cure according to manufacturer's instructions before turning on the water supply.

Tip

Do not heat the copper close to the PVC to avoid melting the PVC pipe. Do not attempt to cool the soldered copper joint with water. This could cause the pipe to crack or leak when water pressure is applied.

Warning

Wear safety glasses and heat-resistant gloves when working around copper soldering.

Things You'll Need

  • Hacksaw
  • Bucket
  • Dry rags
  • Emery cloth
  • Copper-threaded male adaptor
  • Soldering flux
  • Solder
  • Propane torch
  • PVC-threaded female adaptor
  • Teflon tape
  • Pipe wrench
  • PVC primer
  • PVC cement
  • Safety glasses
  • Heat-resistant gloves
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About the Author

Since 1996 Rachel Moon has worked as a technical writer and technical editor in such diverse fields as the semiconductor industry, chemical delivery equipment and video game community management. She has developed curriculum for Occupational Safety and Health Administration general industry training after getting certification from the University of California, San Diego, Southwest Safety Training Alliance and an automotive/diesel vocational school. Moon attended Hofstra University.