How to Connect PEX to Other Pipe Types (Copper, PVC, PB, Faucets, Toilets)

PEX is easy to install, resistant to corrosion, and cost-effective — which makes it a favorite for both new construction and retrofits. But it doesn’t exist in a vacuum. Whether you’re tying into an old copper system or branching out to fixtures, you’ll eventually have to connect PEX to something else. Here’s a breakdown of how to connect PEX to Copper, PVC, PB (Polybutylene), Faucets, and Toilets — with correct, code-compliant methods, step-by-step instructions, and the recommended tools for the job.

Connecting PEX to Copper

There are a few ways to connect PEX to copper — some permanent, some removable. The best choice depends on the application and local code.

Method 1: Push-Fit Fittings (like SharkBite)

• Pros: Fast, no tools needed, removable
  • Use cases: Accessible areas, quick repairs

Steps:

1. Cut the copper pipe clean and square.
   
2. Deburr the end to prevent damage to the O-ring.
   
3. Push the SharkBite fitting fully onto the copper side.
   
4. Insert the PEX into the other side until it clicks.

Method 2: Sweat-to-PEX Adapter

• Pros: Permanent, compact
  • Use cases: Behind walls, long-term installs

Steps:

1. Cut and clean the copper.
   
2. Apply flux and solder a sweat adapter in place.
   
3. Once cooled, crimp or clamp the PEX onto the adapter.
   

Method 3: Press Fitting to PEX Adapter

• Use a press tool to secure one side to copper.
  • Connect PEX with a crimp ring or clamp.

Connecting PEX to PVC

Important note: Do NOT use PVC cement on PEX. It won’t bond, and the connection will fail. Use a mechanical fitting instead.

Method: Threaded Transition

• Pros: Simple, secure
  • Use cases: Permanent installations

Steps:

1. Glue a male or female threaded adapter onto the PVC pipe using primer and cement (PVC side only).
   
2. Wrap the threads with Teflon tape or apply thread sealant.
   
3. Thread on a PEX adapter (brass or poly).
   
4. Connect PEX using a clamp, crimp, or push-to-connect.
   

Method: Push-Fit Fitting (e.g., SharkBite)

• Must be rated for both PEX and PVC.
  • Push one end onto PVC, other onto PEX.

Connecting PEX to Polybutylene (PB)

PB was common in the ‘80s and ‘90s, but it’s no longer manufactured due to long-term reliability issues. So if you’re making repairs or updates to a PB system, it’ll often involve converting to PEX.

Method: PB to PEX Transition Fitting

• Look for fittings labeled PB x PEX or universal push-to-connect (e.g., SharkBite)

Steps:

1. Cut the PB pipe square.
   
2. Insert a stiffener into the PB (if required).
   
3. Push on the PB side of the fitting.
   
4. Attach PEX to the other side using a crimp, clamp, or push connection. 

Connecting PEX to Faucets and Toilets

Connecting to fixtures means making a clean transition from flexible PEX to a solid threaded fitting or valve.

Method: Drop-Ear Elbow with PEX Inlet

• Pros: Anchors to framing, clean finish
  • Use cases: Sinks, toilets, hose bibbs

Steps:

1. Secure a drop-ear elbow (usually ½” FIP) to a stud or bracket.
   
2. Crimp or clamp PEX onto the rear inlet of the elbow.
   
3. Thread on an angle stop or straight valve.
   
4. Connect to the faucet or toilet using a braided supply line. 

You can also use a stub-out bend support or a push-to-connect valve, depending on the install.

Final Takeaways

When connecting PEX to other materials:

• Never glue it — use mechanical fittings.
  
• Always match the fitting to both pipe materials.
  
• Use crimp, clamp, or push connections depending on the job.
  
• Anchor fittings when they’ll be exposed.
  
• Use insert stiffeners if required by code or fitting spec.
  

With the right adapter, you can connect PEX to just about anything. Just about. 

Need fittings or tools? SupplyHouse stocks a full line of transition fittings from trusted brands like SharkBite, Sioux Chief, and Bluefin.