How to Join PEX Pipe
Updated February 25, 2026
Connect PEX tubing using crimp rings, expansion fittings, or push-fit connectors -- the three methods compared with step-by-step instructions for each.
Overview
PEX (cross-linked polyethylene) has replaced copper as the go-to residential water supply pipe. It is flexible, freeze-resistant, corrosion-proof, and cheaper than copper. The main question is how to connect it. Three methods dominate: crimp rings (cheapest, most common), expansion fittings (strongest, code-preferred in many areas), and push-fit connectors (fastest, no tools). Each method is reliable when done correctly. The right choice depends on your budget, the scope of the project, and whether you want to invest in the specialty tools.
What You'll Need
Safety First
- PEX is not rated for outdoor use -- UV light degrades it within months. Keep all PEX inside walls, floors, or ceilings. Short exposed runs in basements and crawlspaces are acceptable if not in direct sunlight.
- PEX cannot connect directly to a water heater. Use a minimum 18-inch copper or brass stub between the heater connection and the first PEX fitting. The heat at the heater outlet degrades PEX over time.
- Do not use PEX with compression fittings designed for copper. The wall thickness is different and the fitting will leak under pressure.
Step-by-Step Instructions
- Cut the PEX Square
Use a PEX tubing cutter ($10-$15) to make a clean, square cut. The cutter works like a ratcheting shear -- squeeze the handle and the blade cuts cleanly through the tubing. A square cut is critical for all three connection methods. An angled or ragged cut prevents the fitting from seating properly and causes leaks. Do not use a hacksaw or utility knife -- they leave rough edges and angled cuts.
Tip: PEX cutters also work on CPVC, polyethylene, and rubber hose. A $10 cutter handles all flexible tubing in your plumbing system. Buy one and keep it in the toolbox permanently. - Method 1: Crimp Rings (Most Common)
Slide a copper crimp ring onto the PEX. Push the brass crimp fitting into the PEX until it bottoms out (the barbs grip the inside of the tubing). Slide the crimp ring to 1/8-1/4 inch from the end of the PEX, positioned over the fitting barbs. Place the crimp tool jaws over the ring and squeeze the handles until they lock. The ring compresses around the PEX and fitting, creating a watertight seal. Use a go/no-go gauge ($5) to verify the crimp diameter -- the gauge should fit over the ring (go side) but not slide over it (no-go side).
Tip: Crimp tool: $30-$60 for a manual ratcheting tool. You need separate jaw sizes for 1/2-inch and 3/4-inch PEX -- most kits include both. The tool pays for itself after 10-15 connections vs hiring a plumber. - Method 2: Expansion Fittings (Strongest)
This method works only with PEX-A (the most flexible type). Use an expansion tool to enlarge the end of the PEX tubing and the expansion ring. Insert the expansion fitting into the enlarged PEX. The PEX contracts back to its original diameter (PEX-A has shape memory), gripping the fitting tightly. The expansion ring adds compression. This creates the strongest residential PEX connection and is the only method that maintains full bore (no flow restriction from the fitting). Expansion tools cost $100-$200 manual, $200-$400 powered.
Tip: Expansion fittings are preferred by many plumbing codes because the connection gets tighter over time (PEX continues to contract). Uponor (Wirsbo) is the dominant brand for expansion PEX systems. The tools are brand-specific. - Method 3: Push-Fit Connectors (Fastest)
Push-fit connectors (SharkBite is the most common brand) require no tools at all. Cut the PEX square, mark the insertion depth on the tube (each fitting size has a specific depth -- check the package), and push the PEX into the fitting until it hits the internal stop. The stainless steel teeth inside the fitting grip the PEX, and an O-ring creates the seal. To disconnect, push the release collar toward the fitting while pulling the PEX out. That is it -- 10 seconds per connection.
Tip: Push-fit fittings cost $5-$15 each vs $0.50-$2 for crimp or expansion fittings. For a full house repipe (50+ connections), the fitting cost adds up fast. Push-fit makes sense for repairs, small projects, and connections in tight spaces where a crimp tool cannot reach. Crimp or expansion is more economical for large projects. - Test for Leaks
After making all connections, turn on the water supply slowly. Walk the entire run and check every connection. Crimp and expansion joints: look for drips at the ring. Push-fit: look for drips at the collar. Any leak means the connection failed -- cut it out and redo. Do not try to tighten a leaking crimp or adjust a push-fit. Remove and start fresh. Leave the system pressurized for 30 minutes and recheck. Some leaks only appear under sustained pressure.
Tip: For large projects, do a pressure test before closing the walls. Cap all open ends, pressurize the system to 80 PSI with a test gauge, and monitor for 2 hours. Any pressure drop means a leak somewhere in the system. Find and fix before drywalling.
Pro Tips
- PEX comes in three types: PEX-A (most flexible, works with expansion fittings), PEX-B (most common, works with crimp rings and push-fit), and PEX-C (least common, works with crimp). PEX-A costs 20-30% more but is easier to work with and the expansion connection is the strongest.
- Color coding: red PEX for hot water lines, blue for cold, white for either. The color is for identification only -- all three are the same material and can carry either hot or cold water.
- PEX manifold systems ($50-$150 for the manifold) run a dedicated line from a central point to each fixture. This eliminates tee fittings in the walls, reduces the number of potential leak points, and allows you to shut off individual fixtures from the manifold. Worth considering for new construction or full repipes.
- Support PEX with plastic hangers every 32 inches on horizontal runs and every 4 feet on vertical runs. PEX expands and contracts with temperature changes -- unsupported runs sag and create noise.
- Do not use pipe dope or Teflon tape on PEX fittings. The connection is mechanical (compression, expansion, or push-fit), not threaded. Tape and dope can interfere with the seal.
When to Call a Pro
PEX connections are DIY-friendly for repairs and small projects. Call a plumber for a full house repipe (permits, code compliance, and pressure testing), for connections to the main water line (requires a licensed plumber in most jurisdictions), or if you are unsure which PEX type (A, B, or C) is already installed in your home.
Frequently Asked Questions
When should I call a plumber to join pex pipe?
PEX connections are DIY-friendly for repairs and small projects. Call a plumber for a full house repipe (permits, code compliance, and pressure testing), for connections to the main water line (requires a licensed plumber in most jurisdictions), or if you are unsure which PEX type (A, B, or C) is already installed in your home.
What are some expert tips to join pex pipe?
PEX comes in three types: PEX-A (most flexible, works with expansion fittings), PEX-B (most common, works with crimp rings and push-fit), and PEX-C (least common, works with crimp). PEX-A costs 20-30% more but is easier to work with and the expansion connection is the strongest. Color coding: red PEX for hot water lines, blue for cold, white for either. The color is for identification only -- all three are the same material and can carry either hot or cold water. PEX manifold systems ($50-$150 for the manifold) run a dedicated line from a central point to each fixture. This eliminates tee fittings in the walls, reduces the number of potential leak points, and allows you to shut off individual fixtures from the manifold. Worth considering for new construction or full repipes. Support PEX with plastic hangers every 32 inches on horizontal runs and every 4 feet on vertical runs. PEX expands and contracts with temperature changes -- unsupported runs sag and create noise. Do not use pipe dope or Teflon tape on PEX fittings. The connection is mechanical (compression, expansion, or push-fit), not threaded. Tape and dope can interfere with the seal.
What tools do I need to join pex pipe?
You will need: PEX tubing cutter ($10-$15), Crimp tool with 1/2-inch and 3/4-inch jaws ($30-$60, for crimp method), Go/no-go gauge ($5, to verify crimp quality), Expansion tool ($100-$200, for expansion method -- PEX-A only), Push-fit fittings ($5-$15 each, for push-fit method -- no additional tools needed), PEX tubing (red, blue, or white -- $0.30-$0.80/foot).
When should I call a professional instead of doing this myself?
PEX connections are DIY-friendly for repairs and small projects. Call a plumber for a full house repipe (permits, code compliance, and pressure testing), for connections to the main water line (requires a licensed plumber in most jurisdictions), or if you are unsure which PEX type (A, B, or C) is already installed in your home.
How difficult is this project?
This project is rated easy. Most homeowners with basic tools can complete it.
How long does this take?
Plan for approximately 5 - 15 minutes per connection. First-timers may need extra time.
How much will this cost?
The estimated cost is $1 - $5 per connection (fittings); $30 - $200 for tools. Costs vary by location and materials chosen.