What the Heck is Pex Piping?

White piping with fittings on a blue surface.

If you're a do-it-yourselfer, you may have heard of PEX piping and wondered if it is something you should care about. PEX is a relatively new development (in North America anyway) in plumbing systems. PEX is an acronym for cross-linked polyethylene pipe and it's replacing traditional copper tubing in a lot of new construction and renovations. Used in Europe for more than 50 years, it started being used in water supply systems in North America in the 1980s as a replacement for not just copper, but also hard plastic pipe systems including PVC, CPVC, and ABS.

What's So Good About PEX?

PEX resists corrosion and the internal buildup of mineral scale that can cause copper pipes to develop tiny pin holes and leak over time. It is resistant to heat and cold, so it can be used for both hot and cold water lines. Even better, it's available in different colors — red for hot, blue for cold as well as basic white, making it easy to know what is in different colored water lines. PEX can also expand and contract, making it resistant to bursting in cold weather. Although no water pipe material can totally resist solid, internal freezing, PEX's ability to give a little provides functionality not possible with hard copper or plastic.

Since, PEX is flexible and comes on a large roll, it can be threaded through holes cut in the framing of a house (similar to copper wire) without requiring any elbow joints or couplers that all need to be soldered and can leak over time. As there is no need to solder multiple joints, PEX can be installed much quicker than traditional copper, and that time saving translates directly into money saving.

It requires only a PEX crimping tool and adapters to connect runs, and adaptors are available to connect PEX with copper and other hard plastic pipes. That makes it a good choice when expanding or upgrading existing plumbing in a home and ideal for a DIY'er who isn't comfortable sweat soldering copper joints.

Are There Some Disadvantages to PEX?

PEX can be damaged by ultraviolet rays, so it can't be used and shouldn't even be stored outside or in areas where it will be exposed to direct sun. The structure of PEX tubing includes an impermeable layer that can be penetrated and end up holding bacteria that can possibly contaminate the water in the line.

Although made from an inert plastic, some people still have concerns that over time chemicals in the pipe could leach out of the plastic and into the water.

Unlike copper tubing that is reused and recycled, at this time, there is no practical way to recycle or reuse PEX tubing. And as a man made plastic product, PEX is made from petroleum. A number of people are concerned about our ongoing dependence on petroleum product in our daily lives.

Understand the different types of tubing and piping is important. Now that you know what PEX piping is, you can decide if it's right for your next project.