Replacing copper pipes with PEX is one of the best upgrades you can make to your home’s plumbing system. I’ve done it myself, and I can tell you it’s much easier than it seems. If you’re tired of dealing with corroding copper pipes, leaks, or high costs of repairs, switching to PEX is a game-changer.
Image by diychatroom
PEX tubing is flexible, easy to install, and resistant to corrosion. Plus, you don’t need to solder anything, which means you can avoid dealing with a torch and open flames.
If you’re tackling a full plumbing replacement or just fixing a section, I’ll walk you through the entire process step by step. Let’s get started.
Why Replace Copper Pipes with PEX?
Copper pipes have been around for decades, but they come with some challenges. Over time, copper can corrode, especially if your water has high acidity.
Freezing temperatures can also cause copper pipes to burst. PEX, on the other hand, is more durable, easier to install, and much cheaper.
Here are the main reasons why many homeowners switch to PEX:
- Cost-Effective – PEX is significantly cheaper than copper.
- Flexible & Easy to Install – You can bend it around corners without special fittings.
- No Soldering Required – PEX connections are made with clamps, crimps, or push-to-connect fittings.
- Corrosion-Resistant – Unlike copper, PEX won’t corrode or develop pinhole leaks.
- Freeze Resistance – PEX expands when water freezes, reducing the risk of bursting.
Tools and Materials Needed
Before you start, gather everything you’ll need. Having the right tools on hand will make the job smoother.
Tools:
- Pipe cutter (for copper pipes)
- PEX tubing cutter
- Adjustable wrench
- Deburring tool or sandpaper
- Tape measure
- Crimping tool or clamp tool (depending on the type of PEX fittings)
- Bucket and towels (to catch excess water)
Materials:
- PEX tubing (red for hot water, blue for cold water)
- Push-to-connect fittings, crimp rings, or clamps
- PEX shutoff valves (if replacing near fixtures)
- Copper-to-PEX transition fittings
- Pipe insulation (for exposed areas)
Step-by-Step Guide to Replacing Copper Pipe with PEX
Step 1: Turn Off the Water Supply
Before you do anything, shut off the main water supply. If you’re only replacing a section of pipe, you can turn off the water to just that part of the house. Open a faucet to relieve pressure and drain any remaining water from the pipes.
Step 2: Cut and Remove the Copper Pipe
Use a pipe cutter to remove the section of copper pipe you’re replacing. Make sure to cut the pipe cleanly and as straight as possible. If there’s any water left in the pipe, use a towel or bucket to catch it.
Step 3: Prepare the Copper Pipe for PEX Connection
If you’re transitioning from copper to PEX, you’ll need a copper-to-PEX fitting. Before attaching anything, clean the copper pipe’s edge with a deburring tool or sandpaper. This ensures a smooth connection and prevents leaks.
Step 4: Connect PEX to Copper
You have a few options for connecting PEX to copper:
- Push-to-Connect Fittings – These are the easiest. Just push the PEX tubing into the fitting until it clicks into place.
- Crimp or Clamp Fittings – Slide a crimp ring onto the PEX, insert the fitting, and use a crimping tool to secure it.
- Threaded Fittings – Some adapters screw onto copper pipes. Make sure to use Teflon tape to prevent leaks.
Step 5: Measure and Cut PEX Tubing
Measure the length of PEX tubing you need, making sure to leave a little extra for flexibility. Use a PEX cutter for a clean, even cut.
Step 6: Install PEX Tubing
Run the PEX tubing where your copper pipes used to be. Since PEX is flexible, you may not need as many fittings as before. Secure it with PEX pipe supports to prevent sagging.
Step 7: Connect PEX to Fixtures
If you’re replacing water lines leading to sinks, toilets, or appliances, install shutoff valves at the fixture connection points. You can use push-to-connect shutoff valves or crimp/clamp connections.
Step 8: Turn the Water Back On and Check for Leaks
Once everything is connected, slowly turn the water back on. Check all fittings and connections for leaks. If you see any drips, tighten the fittings or replace them if necessary.
PEX Fittings: Which One Should You Use?
PEX tubing can be connected using different types of fittings. Here’s a quick comparison:
| Fitting Type | Pros | Cons |
|---|---|---|
| Push-to-Connect | Easy to install, no tools needed | More expensive |
| Crimp Fittings | Secure and affordable | Requires a crimping tool |
| Clamp Fittings | Strong and corrosion-resistant | Requires a clamp tool |
| Expansion Fittings | Creates a tight seal | Requires an expansion tool |
For beginners, push-to-connect fittings are the easiest to use. If you’re doing a large project, crimp or clamp fittings are more cost-effective.
Can You Use PEX for Hot Water?
Yes! PEX is safe for both hot and cold water. Just make sure to use red PEX for hot water and blue PEX for cold water to keep things organized. If you only have white PEX, that works too—it’s just not color-coded.
How Long Will PEX Last?
PEX has a lifespan of 40-50 years, which is similar to copper. It’s resistant to rust and corrosion, so it often lasts even longer in certain conditions.
Do You Need Insulation for PEX?
PEX is more freeze-resistant than copper, but it’s still a good idea to insulate exposed areas, especially in colder climates. Pipe insulation helps prevent freezing and keeps hot water lines more efficient.
Is PEX Safe for Drinking Water?
Yes! PEX is approved for drinking water in the U.S. and meets all health and safety standards. Just make sure to buy PEX tubing that’s NSF-certified for potable water.
Common Mistakes to Avoid
While replacing copper with PEX is straightforward, there are some common mistakes that can lead to leaks or inefficiency.
- Not securing PEX properly – Use pipe supports to prevent sagging.
- Over-tightening connections – This can damage fittings and cause leaks.
- Using the wrong type of PEX – Always use PEX-A, B, or C based on your needs.
- Not checking for leaks – After installation, inspect every connection for drips.
FAQs
Can I connect PEX directly to my water heater?
It depends on local plumbing codes. Some areas require a short section of copper before switching to PEX.
Is it okay to bend PEX tubing?
Yes! PEX is flexible and can bend around corners. Just avoid sharp bends that could restrict water flow.
Can PEX burst like copper pipes in freezing temperatures?
PEX expands when water freezes, reducing the risk of bursting. However, it’s still best to insulate it in cold areas.
How do I know which size PEX to use?
For most home plumbing, ½-inch and ¾-inch PEX are standard. Use ½-inch for fixtures and ¾-inch for main water lines.
Can I replace copper pipes with PEX myself?
Yes! If you’re comfortable with basic tools, replacing copper with PEX is a DIY-friendly project.
Conclusion
Replacing copper pipes with PEX is one of the smartest plumbing upgrades you can make. It’s easier, faster, and much more cost-effective than dealing with traditional copper. With the right tools and a little patience, you can swap out old pipes and enjoy a more reliable plumbing system.
If you’re new to working with PEX, start with a small project and work your way up. Once you see how simple it is, you’ll never go back to copper.
