What Adapter For

How to connect CPVC to galvanized pipe

Use a CPVC x brass threaded transition fitting. It has a glue socket for the CPVC on one end and brass pipe thread for the steel on the other, so the steel threads meet brass.

What fits

A CPVC x brass threaded transition fitting

On the package: CPVC x brass transition, male or female thread to suit the steel pipe

brass transition fittings suit hot and cold water

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CPVC x brass transition fitting PTFE thread seal tape

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  • Shut the water off, then open faucets to drain the pipes before you cut anything.
  • Glue the transition fitting onto the CPVC and screw its brass end onto the steel pipe, with tape on the male threads.
  • A plastic male adapter screwed into a steel fitting is for cold water only. Tighten plastic threads no more than two turns past finger tight, using a strap wrench only.
  • Steel male threads aren’t recommended in a plastic female fitting, because the stress can crack it.

CPVC is glued and galvanized is threaded, so a fitting with a CPVC socket and a brass thread joins them.

Before you start

  • Make sure the steel pipe carries water. Gas supply lines can be black iron or steel pipe too. When in doubt, call a licensed plumber or your local gas company.
  • Rusted fittings and rust-colored water, particularly from hot water lines, are signs of advanced deterioration in galvanized pipe.
  • If a lead service line ever fed this galvanized pipe, lead can cling to its inside and get into the water. Ask your water utility about testing.

Male or female thread

Charlotte Pipe makes its brass transition fittings with male or female thread. Look at the end of the steel pipe: threads on the outside take a female transition fitting, and a steel fitting with threads inside takes a male one.

Common questions

Can I use a SharkBite fitting between CPVC and galvanized pipe?

Not on the galvanized side. SharkBite's Max guide rules out its fittings on galvanized pipe, both push-to-connect and threaded.

How hot can the water be at this joint?

Charlotte Pipe rates its FlowGuard Gold CTS CPVC for water up to 180°F at 100 psi. For another brand, check the pipe maker's rating.

Do I need a dielectric union between CPVC and galvanized pipe?

The codes ask for a dielectric or brass fitting where copper meets galvanized steel. CPVC to steel falls under their plastic pipe rule instead, which asks for an approved adapter fitting.

Keep going

Connecting different pipeCPVC to copperCPVC to PVCPVC to galvanizedPEX to galvanizedPipe thread sizeWhat pipe do I have?

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, US EPA, Charlotte Pipe, International Code Council and Swagelok (plus 3 more).

See all 12 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
  • US EPA, Customer Guide for Identifying Service Lines (2024): scratch and magnet tests, galvanized downstream of lead
  • US EPA, Basic Information about Lead in Drinking Water
  • HUD, Residential Rehabilitation Inspection Guide (2000): water supply piping, fuel supply
  • Charlotte Pipe, Plastics Technical Manual (2026): PVC and CPVC colors, standards, temperature limits, Not for Pressure print, plastic-to-metal threads and brass transition fittings
  • Charlotte Pipe, FlowGuard Gold CTS CPVC submittal and product page: ASTM D2846, 180 F, solvent cement
  • 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)
  • SharkBite (RWC), How to Turn Off Main Water Valve for Plumbing Repairs (SharkBite blog): shut the water off for repairs, then open the faucets to drain the pipes before the work, isolation valves for one fixture, turn the water back on slowly
  • Oatey, How to Replace and Install a Shut Off Valve (project guide): turn off the water supply before removing or cutting off the old valve
  • BrassCraft, Easy 3-Step Gas Connections how-to sheet (BC8472): when in doubt, call a licensed plumber or your local gas company

General guidance from manufacturer and standards data. Parts vary by brand, so check the size printed on the package against what you measured. This site doesn't cover gas lines. If in doubt about gas, call a licensed plumber or your local gas company.