Here you will find some reasons why some people prefer PEX Tubing for Plumbing Systems and why some do not. We generally belive that Plumbing PEX Tubing is much better than Copper for most, if not all, plumbing systems. Of course, there are different types of PEX (A-B and C), different PEX Manifolds systems, diffrent way to connect PEX and more...
The Good Points
Why most People prefex PEX Tubing over Copper - there is a less risk of leaks with PEX Tubing. PEX doesn't degrade like copper, higher PSI rating freezing pipes will still burst, but PEX will be able to handle more freezing water than copper. PEX Tubing is much more resistant to freeze-breakage than copper or rigid plastic pipe. PEX Tubing is cheaper because it takes much less labor to install.
PEX Tubing is quickly becoming the industry standard.
"Corrosive" water, if it had corrosive that it will eat the walls out of copper tubing and you have city water with high levels of corrosive material such as acid.
PEX is cheaper/easier to install and you generally don't need as many fittings.
Flexible PEX tube is manufactured by extrusion, and shipped and stored on spools, where rigid plastic or metal piping must be cut to some practical length for shipping and storage. This leads to several advantages, including lower shipping and handling costs due to decreased weight and improved storage options.
PEX plumbing installations require fewer fittings than rigid piping. The flexible tubing can turn 90 degree corners without the need for elbow fittings, and PEX tubing unrolled from spools can be installed in long runs without the need for coupling fittings.
Attaching PEX tube to fittings does not require soldering, and so eliminates the health hazards involved with lead-based solder and acid fluxes.
PEX is also safer to install since a torch is not needed to make connections.
Water flows more quietly through PEX tube, and the characteristic "water hammer" noise of copper pipe systems is virtually eliminated.
Installing fewer fittings reduces the chances for expensive callbacks.
PEX Tubing "from-scratch" installation is that it's typically installed using a manifold at the water source with a run to each faucet. That approach significantly reduces pressure loss at one faucet when another faucet on the same branch is turned on, as often happens with copper plumbing.
With pex pipe you can use just SharkBite Push Type Fittings. These don't require special tools for installation. SharkBite fittings are considerable more expensive than others but you can fix a leak without ever turning the water off if you like
The Bad Points
PEX is extrordinarily suceceptible to rodent damage and UV. This is true, so don't leave PEX Tubing in the sun and try to keep rodents out of you house.
But due to the flexible nature of the pipe, it can rub as the water is turned on and off and cause a leak. This is true also, but easily fixed - use bend protectors or bend supports for all 90 degrees turns where you can get to the PEX. Also, when running through drilled holes, use PEX protector or something else to help reduce rubbing.