What Adapter For

How to connect galvanized pipe to copper

Use a dielectric union or a brass fitting between the two. The codes name a brass fitting, a dielectric fitting or (IPC) a dielectric union for this joint, and push-to-connect fittings don’t go on galvanized.

What fits

A dielectric union or a brass fitting between the steel and the copper

On the package: Dielectric union (ASSE 1079), pipe thread x copper

the plumbing codes allow a brass (copper-alloy) fitting, a dielectric fitting, or a dielectric union

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Dielectric union, 1/2" FIP x sweat PTFE thread seal tape

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  • Shut the water off and drain the line before you cut anything.
  • The fitting screws onto the galvanized pipe’s threads, and the copper is joined to its other side. The IPC has the copper soldered; the IRC allows any approved joint.
  • Wrap thread tape on the male threads only, the way the threads spiral.
  • SharkBite’s instructions keep its push-to-connect fittings off galvanized pipe, and its Max guide rules out its threaded ends too.

Galvanized pipe ends in tapered pipe thread and copper doesn’t, so something has to change one into the other, and the codes name which fittings may sit between these two metals.

Before you start

  • Make sure the steel pipe carries water. Gas pipe is threaded steel too; if you can’t trace it to a faucet or fixture, leave it alone and ask a plumber.
  • Galvanized pipe that was ever connected below a lead service line can hold lead inside. Ask your water utility about testing.

Common questions

Is a brass fitting enough between copper and galvanized?

Yes. Both the IPC and the IRC list a copper-alloy (brass) fitting as one of the allowed choices.

Keep going

Connecting different pipeWhat pipe do I have?Pipe thread sizePEX to copperGarden hose to 1/2" pipeGarden hose to 3/4" pipeConnect two garden hoses

For a different part on either end, open the adapter finder with this pair picked.

Where we get our information from

The sizes on this page come from published standards and the makers’ own documents. Checked against published data from SharkBite, International Code Council, Swagelok, US EPA and HUD.

See all 7 sources
  • Swagelok, Thread Sealants catalog (MS-14-01): PTFE tape, how to apply
  • SharkBite (Reliance Worldwide), SharkBite Max Installation Guide (2023): approved pipe, depths, removal, burial, warnings
  • SharkBite (Reliance Worldwide), Push-to-Connect Installation Guide (pocket guide): stiffeners, transition fittings, warnings
  • US EPA, Customer Guide for Identifying Service Lines (2024): scratch and magnet tests, galvanized downstream of lead
  • HUD, Residential Rehabilitation Inspection Guide (2000): water supply piping, fuel supply
  • International Plumbing Code 2021, sections 605.23, 605.23.1 and 605.23.2: joints between different materials, copper to galvanized steel (as adopted in South Carolina)
  • International Residential Code 2021, sections P2906.18 and P2906.18.1-P2906.18.3: joints between different materials, PVC service to CPVC (as adopted in South Carolina)

General guidance from manufacturer and standards data. Parts vary by brand, so check the size printed on the package against what you measured. For gas lines or anything inside a wall, use a licensed plumber.