PEX Plumbing 101: What Every Homeowner Should Know.
If you've purchased a newer home or had plumbing work completed in recent years, there's a good chance you've seen PEX plumbing. The flexible red, blue, or white piping has become a common alternative to traditional copper plumbing in homes throughout Washington and across the country.
But what exactly is PEX, how long does it last, and are there problems homeowners should know about? Here's a simple guide to understanding PEX pipes and fittings in your home.
What Is PEX Plumbing?
PEX, short for cross-linked polyethylene, is a flexible plastic piping material primarily used for residential hot and cold water supply lines.
Unlike rigid copper pipe, PEX can bend around corners and obstacles. This flexibility can reduce the number of fittings required during installation and makes it particularly useful when running plumbing through walls, floors, crawlspaces, and other tight areas.
Why Is PEX Plumbing So Popular?
PEX has become popular in residential construction because it offers several advantages.
It is flexible, lightweight, resistant to corrosion, and generally faster to install than traditional rigid piping. Because long sections of PEX can be routed through a home with relatively few connections, there may also be fewer potential leak points along a plumbing run.
PEX is also less likely to burst from minor freezing than rigid piping because it has some ability to expand. However, PEX plumbing can still freeze and become damaged, so pipes in vulnerable areas still need appropriate protection.
What Do Red, Blue, and White PEX Pipes Mean?
One of the easiest ways to recognize PEX is by its color.
Red PEX is commonly used for hot water, while blue PEX is commonly used for cold water. White PEX may be used for either hot or cold water.
The color is primarily there to make plumbing lines easier to identify. A red pipe isn't necessarily a fundamentally different type of PEX than a blue pipe.
Always rely on the manufacturer's markings on the pipe when identifying its specifications and approved uses.
What's the Difference Between PEX-A, PEX-B, and PEX-C?
Homeowners researching PEX plumbing often encounter the terms PEX-A, PEX-B, and PEX-C.
These classifications primarily describe different methods used to manufacture the cross-linked polyethylene.
Each type can have different characteristics regarding flexibility, bend radius, and compatible connection methods. PEX-A is generally known for being particularly flexible, while PEX-B is also widely used in residential plumbing systems.
The important consideration isn't simply whether one letter is "better" than another. The piping, fittings, and connection system should be compatible and installed according to the manufacturer's requirements.
How Are PEX Pipes Connected?
PEX plumbing systems can use several types of connections, including:
Expansion fittings
Copper crimp rings
Stainless-steel cinch or clamp connections
Push-to-connect fittings
Other manufacturer-specific connection systems
Proper installation is extremely important. Even when the PEX tubing itself is in good condition, an improperly installed or deteriorated connection can become a potential leak point.
How Long Does PEX Plumbing Last?
Homeowners commonly ask, "How long does PEX plumbing last?"
PEX is designed to be a long-lasting plumbing material, and properly installed PEX can potentially provide decades of service. However, there isn't one guaranteed lifespan for every PEX system.
Water quality, temperature, pressure, installation quality, environmental exposure, fittings, and the specific product can all influence the life of a plumbing system.
Does PEX Plumbing Have Problems?
Like any plumbing material, PEX isn't completely immune to problems.
Potential concerns can include damaged or kinked tubing, improper support, poorly installed connections, incompatible components, excessive exposure to ultraviolet light before or during installation, freezing conditions, and physical damage.
Another potential issue isn't necessarily with the PEX tubing itself—it can involve the fittings connecting the pipes.
PEX Brass Fittings and Dezincification
Some PEX systems use brass fittings. Certain brass alloys can experience a form of corrosion known as dezincification under particular conditions.
Brass is primarily an alloy of copper and zinc. During dezincification, zinc can selectively leach from the brass, leaving behind a weakened, porous copper-rich structure.
Over time, severe deterioration can potentially contribute to restrictions, weakened fittings, or plumbing leaks.
This doesn't mean every brass PEX fitting will fail. The fitting's composition, water chemistry, installation, age, and other factors can influence whether dezincification occurs.
Can a Home Inspector Identify PEX Plumbing Problems?
During a home inspection, visible and accessible portions of the plumbing system can be evaluated for signs of problems.
An inspector may identify conditions such as visible leaks, corrosion or deterioration around fittings, unsupported piping, damaged tubing, questionable connections, staining from previous leaks, or other abnormalities.
However, much of a home's plumbing system is concealed behind walls, ceilings, cabinets, and other finished surfaces. A standard home inspection is visual and non-invasive, so concealed piping and fittings cannot typically be directly evaluated.
Signs of a Possible PEX Plumbing Leak
Homeowners should pay attention to changes that could indicate a hidden plumbing problem, including:
Water staining on walls or ceilings
Damp areas around cabinets or fixtures
Unexplained increases in water usage
Reduced or changing water pressure
Musty odors or unexpected moisture
Visible corrosion or staining around accessible fittings
Sounds of running or dripping water when fixtures aren't being used
Finding the source of unexplained moisture early can help limit damage to surrounding building materials.
Is PEX Plumbing Good?
PEX is a widely used residential plumbing material and can be a reliable option when properly designed and installed. Simply finding PEX in a home isn't, by itself, a reason for concern.
As with copper, CPVC, or other plumbing materials, installation quality and the condition of the entire system matter.
For homeowners and buyers, understanding what type of plumbing is installed—and paying attention to visible warning signs—can help identify problems before a small leak becomes a much larger repair.
Timber Coast Inspections provides professional home inspections throughout Western Washington. A home inspection can help identify visible plumbing concerns along with issues involving the roof, structure, electrical system, HVAC, crawlspace, attic, and other major components of a home.
From Roof to Dirt, We Check It, So You Don't Regret It.
