Cross-linked polyethylene plumbing, often called PEX, is a flexible plastic offering a replacement for copper and rigid plastic pipes. PEX costs about one-third the cost of copper, is easier to install and resists corrosion.
Plumbers join PEX plumbing to other types of pipe with special connectors. Stab-in fittings offer a quick way to join the pipe by pushing the end of the PEX or copper tubing into the fitting and pulling it back to seal it in place. Compression fittings also work with PEX systems but they are expensive if making several connections. When plumbing an entire home or working professionally, most installers buy a special crimping tool and join the pipes using compression rings.
When designing a whole house plumbing system using PEX, it is common for the plumber to install a manifold. It connects the hot and cold water supplies to several tubes that lead to fixtures throughout the home. With PEX plumbing tubes typically serve a single fixture, rather than branching like copper or polyvinyl chloride plumbing. This type of installation eliminates many of the connections that are sources of leaks.
The tubes are available in red and blue allowing for color-coding of the hot- and cold-water plumbing systems. White tubing is also available for installers who prefer a single color for both systems.