How to Join Dissimilar Pipes

Avoid leaks and corrosion at pipe transitions

Making connections

When you go to add or replace plumbing lines in a house that's more than 10 years old, chances are you won't find new pipes that are the same kind as the old ones. That's no big deal—hardware stores and home centers carry hundreds of different kinds of transitional fittings to help you make the connections. What is a big deal is that those hundreds of different kinds of fittings don't all install the same way.

Some fittings need to be soldered; others take just a wrench or pliers. Several require specific crimping tools, and there are newer styles that simply push together. We asked a master plumber how he deals with the ones he encounters the most, but don't run all over town trying to find the exact fittings we show here. There are usually several suitable solutions using parts available at a local hardware store or home center.

Icemaker line

Water filter line

PEX to copper


Plastic to galvanized steel


Copper to CPVC

Take Them to the Store

Save yourself repeated trips to the home center or hardware store by taking a small chunk of each pipe you plan on using to the store.

Buy approved products

Shielded rubber couplings

Copper to galvanized steel

Push fittings are immediate

Control valves for joinery

Don't guess

Required Tools for this Project

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

  • 4-in-1 screwdriver
  • Adjustable wrench
  • Wire brush
  • Pipe wrench
  • Plumbers tape
  • Slip joint pliers
  • Tube cutter
  • Wrench set

You'll also need a cinch clamp tool.

Required Materials for this Project

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

  • Pipe adapters, couplings and fittings
  • Solder and flux
  • Pipe dope
  • Pipe glue

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