CPVC is the worst way to go IMO. Builders love it because it's cheap! That's the only reason anyone would ever use it. Where does all the glue residue go after it's installed? A certain amount, (be it even a tiny little trace, scientifically measured amount) goes right into you glass. Any amount is to much toxic glue for my families or clients. Not to mention, if you ever want to add on anything, like tap into the plumbing system for a new water line for a ice maker. You have to shut down the entire house for 24 hours to let the piping's glue set. Lastly the stuff is fragile, for example someone accidentally grabbed, kicked, or hung some clothes to dry on the pipes, it could just plain snap and flood your house because the pipe is just glued into the joints/fittings, I have heard of cpvc pipe popping right out of joint simple because someone didn't use enough glue. CPVC has no "easy" visual indication that it has been installed properly, where as you can see an visual indication for both copper and pex the job was done correctly. Clearly you can see I don't like the stuff, but when installed properly it will transport, which is it's only requirement.
Copper is great, but extremely expensive, and labor intensive to install properly. Also naturally occurring minerals in well water, and even town provided water. Aka "city water" can and will break down the copper at it's weakest points over time. The pex water system prevents accelerated corrosion and deterioration between pipes made from dissimilar metals, (meaning, well systems should use pex- no question) Copper is ok with well systems as long as dielectric unions
are installed throughout the well system, but that's costly and takes a lot of time to install properly.
PEX, is currently the best system IMO. It's getting more expensive now that it has gotten so popular in the industry, but still much less expensive than copper. It's very reliable when installed properly, and much more durable than cpvc because the joints on Pex fittings allows it to flex, where the cpvc doesn't, Pex is also much better against premature break down that is associated with well water. Faster, Easier, More Reliable = why the plumbing industry has gone bonkers over the pex system.
Note: be careful when buying PEX, many cheap imports from China have come in, and are being sold every where (online for very low prices) and I expect to see some problems associated with these products in the future. Much like the problems with China producing cheap PVC DWV (drain-waste-vent) piping in the 80's, before we temporally outlawed it at our ports, and created a new standardized system that stamped out all the shorty PVC from even entering America after that point. You should ONLY buy pex in plumbing supply stores IMO. Check out my site if you want to learn more about plumbing, but more specifically water heating & water heaters. WaterHeatingInfo.com