Another PEX question
The dishwasher I'm replacing (in another thread) has a PEX tee and valve in the crawl space off the 1/2" copper supply to the kitchen sink. Now I seem to recall some problem with PEX plumbing in the past, and this fitting is the same age as the dishwasher: 25 years or so.
A web search didn't uncover any issues, but there were references to PEX made with and w/o an "oxygen barrier".
Should the tee and fitting be replaced or is there any way to tell if the piping has the so-called oxygen barrier?