I have a question related to my other post, Plumbing question - converting copper to CPVC. The instructions for installing the fixture say to use 1/2" IPS pipe or 1/2" copper. Is IPS the same thing as CPVC? Is the 1/2" the Inside Diameter? I have some 1/2" PVC (not CPVC) that I used on drain pipes and it measures about 11/16" Inside Diameter and 13/16" Outside Diameter. It says 1/2" on the side of it, but nothing is 1/2" so I'm totally confused about why it says 1/2". I bought some 1/2" CPVC (which says 1/2" on the side of it) and it measures about 7/16" Inside Diameter and 5/8" Outside Diameter. Is this the right stuff to use on the bathtube fixture?