If I were building new, I'd go PEX.

PEX, for sure.

I wonder if the issue is more with the fittings used to connect the system? I would question him further.

@outpaientzero That's very helpful, thank you! I knew about the PEX A/B/C distinction, but not the numbers that come after. Our water is chlorinated, from municipal water supply.

Custom new build, why not copper? Jake?

" why not copper? "

Cost. Pex is considerably less expensive.

@venmar Copper is nice - and in a custom build I'd at least check it as an option. That said, when the starting point is CPVC, copper doesn't sound like it's an option. PEX is an upgrade from CPVC supply lines in my mind.

I'd lean copper if rodents are a potential problem.

You can also do a combo if it makes sense. You might do a copper main to a manifold, for example, and branch off with PEX.

From an installer's perspective, CPVC requires the least skilled workers, PEX a little more, and copper requires workers who can solder joints reliably (older, more experience, and more expensive). Not having a torch going on a job site is a plus from an insurance perspective.

Part of my bias against CPVC supply lines is that it does allow the most green workers to do the work - and that often shows in the finished product.

Definitely PEX. Copper is too expensive in regards to material and labor. CPVC will get brittle over time and fail.

PVC drain plumbing is the standard nowadays, both in regards to cost and labor. Maybe that's what the builder meant. If the build really did mean he "typically uses PVC" for water supply plumbing, that would be a huge red flag.

HU-867564120 - that was a typo on my part, should have been "we typically use CPVC" and this was in regards to supply plumbing of the house, not drain.

When talking about getting brittle over time and failing, this is like, over decades, correct? This isn't a forever home for us, maybe 15-20 years.

You are building a home - something that's going to last 100 years or more. Build it with that timeframe in mind, not 15-20 years.

Virtually everyone on here has said that PEX is the way to go given that copper is probably not in the realm of possibilities. Unless you have a known issue with rodents, you should go with PEX.

Likewise, I would stay away from vinyl siding, I would insist on good insulation and high efficiency hvac (probably heat pump) and an electric charging rough-in for a fast charger in the garage. If you are in the South, SW, no exposed plumbing. Again, you are building for the next 100 years or more.

PEX is my preference, based on this thread and other research, I'm just asking what the actual longevity of CPVC is. Every comparison I see between the two talks about CPVC turning brittle, and makes it out like it'll shatter if you look at it wrong, but obviously it can't be that bad?

I'm also preparing for the what if scenario of, I request price difference for PEX, and it comes back way off. Maybe the plumber hates working with PEX and quotes an F U price, for example. Then do I care enough to push back and fight it, or do I just say ok, CPVC is fine/not worth the price change/fight.

I'll ask the new neighbors if they've had any rodent issues. It's a suburban area, so there are some squirrels and rabbits, but not sure about mice or other critters.

If it comes back a stupid price tell your GC to get a different plumber.

PEX should be about the same as CPVC.