Transitioning to PEX Plumbing

red and blue PEX plastic pipes running toward copper pipes
What You'll Need
Sections of 1/2-inch PEX tubing
Push-fit straight couplings
Push-fit tees
PEX pipe cutter
Copper tubing cutter

Cross-linked polyethylene (PEX) is a form of plumbing piping that rose in popularity in the 2000s. Until that point, copper piping had largely been the plumbing of choice. But as your old copper piping begins to need replacing, you can replace sections of your old piping with PEX—or completely redo the system altogether. To replace your copper piping with PEX, you will need to open the walls up.

Back in the day, replacing a section of piping meant that you had to pull out a blow torch and sweat-solder copper pipe together. Thankfully PEX is much easier to work with and is significantly more DIY friendly. PEX uses crimp-ring and a crimper tool for connectors, or push-to-fit connectors. Make sure that you have all of your PEX and connectors ready to go before you start knocking down sheetrock.

Pipe Problem Solutions

When you run into a problem with your copper piping you can take one of three approaches: First, you can repipe your entire home with PEX (disconnect and pass the current copper piping—this may be a pricier option, but it’s usually smart in the long run). Alternately, you can spot-treat a leaky copper pipe by cutting out the damaged section and replacing just that section with PEX and push-to-fit connectors. Finally, you can replace a run of piping with PEX which essentially means that when you find a leak, you replace an entire section of piping, not just the affected area. This is a good middle ground if you’re not ready to re-pipe an entire home.

four plastic pipes running along a wood surface

Replacing a Pipe

Turn off Water Source

Once you have identified the source of the problem, turn off the water in your home. This will require a little planning on your part, so make sure you don’t need to run the dishwasher or a family member isn’t showering before you twist the knob. While there will still likely be standing water in your pipes, it will be a small amount as opposed to the flood that would overtake your home should you cut a pipe without the water being turned off.

Cutting Copper

Take a copper cutter and cut both ends of the section of piping you want to replace. PEX comes in standard ten-foot sections, so don’t cut a section longer than you can replace. If you are cutting a vertical section of piping you will need to support the remaining piping above to keep it from crumbling or falling down the wall. You can do this by securing it with a string or a wire — or by having someone else hold it.

If the section you are cutting has branch lines, you will need to sever them too. You may need a wrench to do so.

hands holding a copper pipe with cutting tool

Clean it Up

You need to make sure that the edges of the old copper piping are perfectly smooth to prevent problems. Use a deburring tool to smooth the edged before you try to test the PEX piping on the spot.

Replace with PEX

Next, replace the section with your PEX piping. Cut the piping just a little bit longer to allow for flex. Use a push-fit straight connector to connect the copper end to the new PEX piping. Make sure the new section of pipe is fully seated in the connector and then repeat on the other end. If the old section of copper connected to a supply line, you will need to reconnect the new PEX pipes now. Cut the PEX piping with a tubing cutter then use a t-fitting to connect to the new line. If you would like to replace more than the leaking section of the pipe, now would be the time to do so.

As you DIY your new pipes, be cautious and meticulous. It’s important to watch out for electric wiring and to go slow so you don’t make a mistake. Replacing your piping can be daunting, but once you get the hang of it, you’ll be the PEX master.