How to Replace Copper Pipe With PEX

Replacing old copper pipes with new PEX piping is a great way to upgrade and modernize the plumbing in your home. PEX (cross-linked polyethylene) is flexible, durable, and resistant to scale buildup and corrosion. Installing PEX pipe is also faster and easier than working with rigid copper pipes that need soldered joints. With some basic tools and materials, you can replace copper with PEX piping yourself.

Gather the Necessary Materials

Before starting the PEX replacement job, gather all the supplies you will need. Here are the basic materials required:

  • PEX tubing – Make sure to get enough PEX pipe in the right sizes to re-plumb the entire section you want to upgrade. PEX is available in red, blue, and white colors.
  • PEX fittings – You will need PEX adapters, couplers, tees, elbows, and end caps to connect the pipes. Fittings are available in elbow, tee, coupler, and cross styles.
  • PEX support hangers – These plastic or metal hangers hold up PEX pipes.
  • Tubing cutter – A sharp tubing cutter tool is essential for neatly cutting the PEX tubing to size. Avoid hacksaws which will crush and deform the pipe ends.
  • Crimp tool and rings – The crimp tool securely joins the PEX tubing to the fittings. You need the correctly sized crimp rings too.
  • Manifolds – PEX manifolds with multiple ports to connect hot and cold supply lines.
  • Shutoff valves – Ball valves to control water flow to fixtures once PEX is installed.
  • Pipe insulation – Insulate hot water PEX pipes to minimize heat loss.

How to Plan the New PEX Layout

Carefully plan out the new PEX piping layout before getting started. Here are some tips:

  • Evaluate the existing copper piping – Inspect the current layout and how copper pipes connect to fixtures. This will help plan the new setup.
  • Plan a home run layout – PEX should be run directly from a central manifold to each fixture. Avoid daisy chaining connections.
  • Map optimum manifold locations – Position manifolds close to the water heater and main incoming supply lines.
  • Label fixtures – Mark each sink, toilet and appliance you will connect for easy identification.
  • Measure runs – Measure the required length for each PEX segment to avoid wastage. Add some extra length.
  • Draw a pipe schematic – Creating a map of the new piping layout will serve as a handy reference during installation.

Thorough planning and measurement will save a lot of time and headaches later during the PEX installation process.

How to Cut Copper Pipes Prior to PEX Installation

Before running any new PEX tubing, the existing copper pipes need to be cleanly cut back. Follow these steps to cut copper pipes in preparation for the PEX replacement:

  • Shut off the main water supply and open all faucets to drain the lines.
  • Starting at the water heater, cut the hot and cold copper lines using a mini-hacksaw.
  • Make square cuts, leaving at least 6 inches of copper pipe sticking out.
  • Use a utility knife to remove any burrs or edges from the cut pipe ends.
  • Cap the open copper ends temporarily to block debris from entering.
  • Flush the pipes well once the water is turned back on to clear out any metal shavings.

Cutting the old copper pipes properly will leave clean, ready-to-connect endings to attach the new PEX piping to.

How to Install PEX Manifolds and Main Runs

PEX manifolds provide centralized connectors to distribute water to the various branch lines in the home. Here are the steps to install PEX manifolds:

  • Mount the manifolds near the water heater using screws or brackets.
  • Install shutoff valves before the manifold to control main water flow.
  • Attach the copper hot and cold lines to the manifold inlets using unions or elbows.
  • Run appropriately sized PEX tubing from the manifold outlets to each fixture location. These are the main home run lines.
  • Use hangers to support the long vertical and horizontal PEX main runs every 32 inches.
  • Label the end of each main run line by fixture for easy identification.

Taking the time to neatly install the manifolds and main PEX tubing runs will really help the overall aesthetics and functionality of the system.

How to Connect PEX Tubing to Fixtures

The final step is to connect the end of the home run PEX tubing at each fixture. The basic process is:

  • Confirm the PEX line is labeled for the correct fixture.
  • Make any necessary bends using a PEX tubing bender. Avoid kinks.
  • Cut the PEX tubing to the precise length needed for the final connection.
  • Slide on the appropriate PEX fitting and crimp ring.
  • Use the PEX crimp tool to securely join the tubing to the fitting.
  • Connect the finished PEX fitting to the fixture valve or shutoff valve.
  • Ensure all connections are watertight. Test each one before moving on.

With all the PEX tubing runs connected, inspect the overall installation for any issues before reopening the main water supply. Then check the system under pressure for leaks.

FAQs About Converting to a PEX Plumbing System

Some common questions that arise when replacing copper pipes with PEX are:

Is PEX pipe better than copper?

PEX is more flexible, cheaper, and easier to install than copper. PEX also withstands corrosion and scale buildup better. However, copper is more durable and has a longer lifespan if installed correctly.

How long does PEX piping last?

Quality PEX tubing can last over 50 years. PEX has only been used for about 25 years to date but tests project an average lifespan of 70-100 years.

Is PEX plumbing safe for drinking water?

Yes, PEX is certified safe for potable drinking water supply lines. The crosslinked polyethylene material is inert and does not leach chemicals.

Can I install PEX myself?

With some basic DIY plumbing experience and tools, PEX can be self-installed by homeowners. The push-fit connections make PEX simpler than sweating copper joints.

How do I transition from copper to PEX?

Usemale copper adapters to connect PEX lines to existing copper pipes. You can also cap copper and run all new PEX home runs using manifolds.

Can I mix copper and PEX pipes?

It is possible to have a hybrid system using PEX only for new additions. Use adapters to join copper and PEX at transition points.


Replacing old copper plumbing with new PEX piping is a worthwhile upgrade for homeowners. PEX systems are easy to customize, simple to install, and provide reliable service for decades. With proper planning and materials, you can tackle a DIY PEX repiping project and enjoy the benefits of modern, leak-free plumbing.

How to Replace Copper Pipe With PEX

Replacing rigid copper pipes with flexible PEX tubing is an excellent way to update old plumbing and gain the advantages of a durable, easy to install piping system. Here’s a step-by-step guide on how to replace copper pipe with PEX.

Gather Necessary Materials

  • PEX tubing – Select the right size for main lines and branches. Get enough to repipe the whole section.
  • PEX fittings – Elbows, tees, couplers, adapters. Match fittings to pipe diameter.
  • PEX crimp tools and rings – To securely connect tubing and fittings.
  • PEX pipe cutter – Cuts plastic tubing without crushing or deforming.
  • Manifolds with ports – For central water distribution to PEX lines.
  • Hangers and clamps – To support and secure PEX tubing.
  • Valves and insulation – For controlling fixtures and insulating hot lines.

Plan the New PEX Layout

  • Evaluate current copper piping runs and fixture connections.
  • Design a ‘home run’ layout with direct lines between manifold and fixtures.
  • Determine optimum location for PEX manifold(s) near main lines.
  • Make a schematic of the planned PEX layout for easy reference.
  • Label fixtures to connect and measure tubing lengths needed.

Cut Back Copper Pipes

  • Shut off main water supply, drain plumbing lines.
  • Cut copper pipes at least 6 inches back from connections.
  • Remove any burrs from the cut ends. Cap temporarily.
  • Flush system thoroughly once water is back on.

Install PEX Manifolds and Main Runs

  • Mount manifolds near water heater using brackets.
  • Install shutoff valves before manifolds to control water flow.
  • Connect hot and cold copper lines to manifold inlets.
  • Run PEX main lines from manifold outlets to fixtures.
  • Use hangers to support PEX pipes every 32 inches vertically and horizontally.
  • Label each PEX main run line with corresponding fixture.

Connect PEX Tubing to Fixtures

  • Confirm labeled PEX line matches intended fixture.
  • Make any necessary bends with tubing bender. Avoid kinks.
  • Cut PEX tubing to required length for final connection.
  • Slide on PEX fitting and crimp ring. Crimp securely.
  • Attach finished PEX fitting to shutoff valve or fixture.
  • Check for leaks. Open main water when all connections are made.

Converting from copper to PEX piping takes planning and care. But the benefits of performance and ease of installation make it a worthwhile plumbing upgrade.

Frequently Asked Questions About Converting to PEX

Is PEX better than copper plumbing?

PEX tubing is generally better than copper for most residential uses. The flexible plastic material is cheaper, easier to work with, and resists corrosion.

What are the downsides of PEX piping?

PEX is not as durable or heat resistant as copper over the very long term. But it can still last 50+ years if installed properly.

Is PEX pipe safe for drinking water?

Yes, PEX has been certified safe for potable water delivery after extensive testing. The crosslinked polyethylene is inert.

What’s the best way to transition from copper to PEX?

Use male copper adapters to connect PEX to existing copper lines. You can also cut back copper and run all new PEX with manifolds.

Can I install a PEX plumbing system myself?

With some DIY ability and the right tools, homeowners can self-install PEX lines. The push-fit connectors are simpler than soldering copper.

How long does it take to repipe a house with PEX?

Depending on house size, it typically takes 2-3 days for a first-time DIYer to do a complete PEX repipe. Pros can complete it in a day.

Does PEX pipe require special maintenance?

Beyond routine plumbing inspection and flushing, PEX does not require much special maintenance. It is corrosion and scale resistant.

Converting from copper to PEX can modernize your home’s water delivery system with minimal fuss. Pay attention to the planning details and take care with the installation for best results.

Final Thoughts on Replacing Copper Pipes with PEX

  • Check local plumbing codes – Some code requirements may apply for PEX installs. Research before starting.
  • Consider repiping in sections – Whole-house PEX replacement is daunting. Tackle it in phases.
  • Hire a pro if uncomfortable – Repiping is complex. For novice DIYers, consider hiring a professional.
  • Update other plumbing components – Replace worn washers, valves and fixtures at the same time.
  • Properly dispose of copper piping – Recycle the old copper tubes at approved metal recycling centers.
  • Be patient – Allow plenty of time to complete all steps without feeling rushed.

With its ease of use, longevity and resistance to corrosion, PEX is a smart upgrade over traditional copper plumbing. Follow proper planning and installation techniques to maximize performance. Thoroughly researching the process beforehand ensures the best results.