PEX, or cross-linked polyethylene, is a flexible plastic tube used for hot and cold water lines, radiant floor heating, and other plumbing jobs. It’s affordable, resists corrosion, bends easily, and is usually simpler to install than copper. PEX makes getting water where you need it less of a hassle.
Why PEX Is Becoming a Homeowner Favorite
If you envision your home’s plumbing as a maze of shiny copper pipes, you might be surprised to learn that many newer houses use flexible PEX plastic tubing behind the walls.
It has become one of the most popular alternatives to traditional copper and other pipes, especially in new homes, remodels, and whole-house repiping projects.
Here’s what homeowners need to know about PEX before deciding if it’s the right choice for their plumbing project.
PEX Defined
PEX stands for cross-linked polyethylene. This type of plastic is specially treated to be stronger, more durable, and better at handling heat than regular polyethylene.
Unlike copper or other rigid pipes, PEX is flexible. It can bend around corners and weave through walls and floors, so you need fewer fittings and less cutting or connecting.
PEX is commonly used for:
- Hot and cold water supply lines
- Bathroom and kitchen plumbing
- Whole-home repiping
- Radiant floor heating systems
- Water service lines in some applications
- Ice maker and refrigerator water lines
Instead of struggling to fit a rigid pipe around every corner, you can usually guide PEX where it needs to go.
The Difference Between PEX-A, PEX-B, and PEX-C
You might see PEX labeled as PEX-A, PEX-B, or PEX-C. These letters show the different ways the tubing is made, which affect its flexibility and other features.
You don’t need a chemistry degree to tell them apart:
- PEX-A: The most flexible of the three and generally the most resistant to kinking. It’s favored for applications where flexibility is important.
- PEX-B: Somewhat stiffer than PEX-A and often less expensive. It’s widely available and commonly used in residential plumbing.
- PEX-C: Generally less flexible and less common in residential applications.
PEX-A isn’t always better than PEX-B or PEX-C. Each type has its own benefits, and the best choice depends on your project, the connection system, cost, and your plumber’s preference.
For most homeowners, the main question is whether PEX is right for the job, not which type of PEX is used.
PEX vs. Copper vs. CPVC
Copper and CPVC are also used for water lines, and each material has its own pros and cons.
PEX
- Less expensive than copper
- Flexible and easy to route through walls and floors
- Highly resistant to corrosion
- Doesn’t require soldering
- Can be relatively DIY-friendly for smaller projects
- Can be vulnerable to rodent damage
Copper
- Extremely durable when conditions are favorable
- Rigid, so it requires more fittings around corners
- More expensive than PEX
- Can corrode or develop pinhole leaks under certain water conditions
- Requires soldering or specialized fittings for many installations
CPVC
CPVC stands for chlorinated polyvinyl chloride. You don’t need to remember the full name — just know it’s another kind of rigid plastic plumbing pipe used for hot and cold water.
- Less expensive than copper
- Resistant to corrosion
- Easier to work with than copper in some situations
- Less flexible than PEX; can become brittle with age or impact
Why Homeowners Are Choosing PEX
PEX Costs Less Than Copper
PEX tubing is cheaper than copper, and the savings can be significant on a large plumbing project.
Installation can also be less expensive because PEX is lightweight and flexible, and requires less cutting, soldering, or fitting than copper.
You don’t need a torch, which is great if you’d rather not deal with an open flame under your kitchen sink on a Saturday afternoon.
PEX Is Flexible
This is one of the main reasons people choose PEX.
Instead of using a rigid pipe and a fitting whenever the plumbing turns a corner, installers can often bend PEX around obstacles and through tight spaces. This usually means fewer connections and a quicker installation.
Having fewer connections also means there are fewer vulnerable places where leaks might start.
PEX Doesn’t Rust or Corrode Like Metal Pipe
PEX doesn’t rust and is very resistant to corrosion. This is especially helpful in places where the water can damage metal pipes.
Homeowners in Southern California may find this helpful if they have hard water and older pipes that are showing signs of wear.
PEX can still have issues, but corrosion is not a major problem for it.
PEX Handles Temperature Changes Well
PEX is made for both hot and cold water. It also handles freezing better than rigid pipes because it can expand slightly if the water inside freezes.
But that doesn’t mean PEX is freeze-proof. A long freeze can still damage the pipes and connections.
In most Southern California homes, freezing isn’t a big concern. But if you have a mountain home, a vacation property, or exposed pipes in a colder area, it’s worth considering.
PEX Is Easier to Install Than Copper
PEX doesn’t need traditional soldering. Depending on the system, you can connect it with crimp rings, clamp rings, push-fit fittings, or expansion fittings.
That makes PEX an attractive option for both professional plumbers and experienced DIYers.
Still, just because it’s easier to install doesn’t mean mistakes can’t happen. A bad connection can still cause a big leak inside your home.
PEX Is Designed to Last
PEX lasts for decades when installed and used as the manufacturer recommends. Many brands offer warranties of 25 years or longer.
How long PEX lasts depends on factors such as how it’s installed, water temperature, sunlight exposure, water chemistry, and the quality of the materials and connections.
Unlike copper, PEX doesn’t develop rust or the same type of pinhole corrosion that can eventually cause leaks in metal piping.
Downsides of PEX
PEX has many advantages, but no plumbing material is perfect.
It Doesn’t Like Sunlight
PEX should be kept out of direct sunlight and isn’t meant for outdoor use unless it’s specifically rated for it. Sunlight can break down the material over time.
In short, PEX should be behind walls, under floors, or otherwise protected, not left out in the sun.
Rodents Can Damage It
Rodents can sometimes damage PEX. If you have a rodent problem, keep this in mind when planning your plumbing installation.
It Isn’t Appropriate for Every Application
PEX is common for home water supply plumbing, but sometimes another material is better. Local plumbing codes, the type of PEX, and the manufacturer’s instructions are all important.
A plumber can also help determine which type of pipe makes the most sense when connecting PEX to existing plumbing made of copper, galvanized steel, CPVC, or other materials.
It Still Needs Proper Installation
PEX is good for some DIY projects, but not every plumbing job should be done yourself.
An experienced handy homeowner might be able to replace an easy-to-reach section of tubing. But repiping a whole house, working on the main water line, or dealing with pipes inside hard-to-reach walls is much more complicated.
If a mistake could flood your walls or floors, it’s worth hiring a professional.
Where PEX Is Used in a Home
PEX is surprisingly versatile. You may find it supplying water to:
- Kitchens: Sinks, refrigerators, and ice makers
- Bathrooms: Sinks, toilets, showers, and tubs
- Laundry rooms: Washing machine supply lines
- Whole-home plumbing systems: Hot and cold water supply lines
- Radiant heating systems: In-floor hydronic heating
- Repiping projects: Replacing aging or damaged supply plumbing
You can connect PEX to other types of plumbing, which is helpful if you’re updating an older home and don’t want to replace every pipe.
Using PEX in Southern California Homes
For many Southern California homeowners, PEX offers several practical advantages.
Older homes often have copper, galvanized steel, or other pipes that may have leaks, corrosion, or mineral buildup after many years. PEX is a good replacement because it’s flexible, resists corrosion, and usually costs less to install than copper.
PEX also works well for remodeling projects where you need to run plumbing through existing walls and floors.
However, the best material depends on your home, the current plumbing, the project, and local building codes. If you’re thinking about repiping your whole house, have a professional check things out before choosing based only on price.
A Good Plumbing Material for Experienced DIYers
PEX is much easier for experienced DIYers than copper because you don’t have to solder the connections. For a simple project, you might only need a PEX cutter, the right tool for connections, and some fittings.
But plumbing isn’t the best place to learn by trial and error. Before you start, check local permit rules and make sure you have the right fittings and connection method for your PEX.
For big plumbing jobs, especially those involving the main water supply or extensive work inside walls, a licensed plumber can ensure everything is safe and up to code.
The Bottom Line on PEX Pipes
PEX is popular for good reason. It’s flexible, corrosion-resistant, less expensive, and easier to install than many traditional plumbing materials. For homeowners, this often means plumbing projects are faster and less expensive.
If you’re replacing old plumbing, remodeling a kitchen or bathroom, or planning to repipe your whole house, PEX is worth considering. Just be sure the material and installation method suit your home and comply with local plumbing codes.
If you’re not sure what’s behind your walls, start there. Knowing what kind of plumbing you have makes it much easier to decide what to use as a replacement.
FAQs About PEX Pipes
Q: What does PEX stand for?
PEX stands for cross-linked polyethylene. It’s a type of flexible plastic tubing that’s specially manufactured to be stronger and more heat-resistant than ordinary polyethylene.
Q: Is PEX safe for drinking water?
Yes. PEX products intended for drinking-water applications are tested and certified to applicable drinking-water safety standards. Look for products certified for potable water use, such as those meeting NSF/ANSI 61 requirements.
When installing new plumbing, flush the lines before using the water for drinking or cooking.
Q: How long does PEX pipe last?
PEX is designed to last for decades when properly installed and used in accordance with the manufacturer’s specifications. Many PEX manufacturers offer warranties of 25 years or more, although actual service life depends on installation, temperature, sunlight exposure, water chemistry, and other conditions.
Q: Can PEX be used for hot water?
Yes. PEX is commonly used for both hot and cold water supply lines. However, the connection between PEX and a water heater must follow applicable plumbing codes and the manufacturer’s requirements. Some installations require a different material or a specific transition fitting near the heater.
Q: Is PEX better than copper?
Neither material is automatically better for every situation. PEX is generally less expensive, more flexible, and easier to install, while copper is extremely durable and has been used successfully in residential plumbing for decades.
The best choice depends on the home, water conditions, installation, budget, and local requirements.
Q: Can I install PEX myself?
PEX is one of the more DIY-friendly plumbing materials, particularly for smaller, accessible projects. It doesn’t require traditional soldering, but you still need the correct tools, fittings, and connection method.
For whole-house repiping, main water lines, or plumbing that’s difficult to access, hiring a licensed plumber is usually the safer choice.
Q: What is CPVC, and how is it different from PEX?
CPVC stands for chlorinated polyvinyl chloride. It’s a rigid plastic pipe commonly used for hot and cold water supply lines.
Unlike flexible PEX, CPVC is rigid and must be cut and connected with fittings when the plumbing changes direction. Both materials are corrosion-resistant, but PEX is generally easier to route through tight spaces.
Q: What’s the difference between PEX-A, PEX-B, and PEX-C?
PEX-A, PEX-B, and PEX-C are different types of PEX made using different manufacturing methods.
- PEX-A: Generally the most flexible and resistant to kinking.
- PEX-B: Somewhat stiffer and often more affordable and widely available.
- PEX-C: Generally less flexible and less common in residential applications.
The letters don’t mean that one type is universally better than the others. The best option depends on the particular plumbing project and connection system.
