PEX has become a contender for use in residential water plumbing because of its flexibility. It can be turned 90 degrees either by a wide turn or using an adapter; PVC, CPVC and copper all require elbow joints. It also has the capacity to run tubing directly from a distribution point continuously to the desired outlet fixture without cutting or splicing; this reduces the need for potentially weak and costly joints. The cost of material can also be approximately 20% less than alternatives, and installation is much less labor intensive.

PEX tubing has also become the most popular way to transport water in hydronic radiant heating systems. In these systems PEX is used to carry hot water from the heat source to the baseboard or radiators. PEX tubing with an oxygen barrier must be used when ferrous components are present in a radiant heating system. If an oxygen barrier is not used in these systems, the ferrous components will rust. However, if a radiant heat system does not contain ferrous components standard PEX tubing may be used.