David, all the "experts" say to NOT use PVC for compressed air lines, so I don't recommend you do it. Another case of "do like I say; not like I do."/w3tcompact/icons/laugh.gif I used material on hand at the time (over 3 years ago) and know a lot of other folks have done the same with no problems, but if I were going to buy the material to do it, I'd probably use rigid copper and sweated joints. And low pressure waterlines come apart? Are you talking about the joints pulling apart; not the line itself breaking? If so, yes, I've seen a bunch of them; always because of poor workmanship in putting them together in the first place.