I'm OK with multi-decade life for certain things like roofs or fences or siding. But not for plumbing. What happens, one day the pipe just bursts and destroys the house?
Depends. PVC tends to fail catastrophicly so if you are nnot home to get the valve off you are in trouble (odds are you are home, as pressure changes from turning a faucet off are likely to cause this. Metal pipes develop slow leaks over time so if you look at the house monthly you will probably catch issues before they do too much damage. So long as PEX isn't exposed to UV is is probably good forever (but the joints
are not).
Floods generally will not destory a house structure but it will destory the drywall, carpet, and the like so the cleanup is expensive.
