I have a fresh water plumbing question. Our motorhome has the grey piping throughout. Recently we replaced the kitchen sink. When I went to Home Depot I was given the newer white type PEX pipe. I already have the crimper and crimp rings. As I made the repair I noticed the new brass fittings were snug in the white pipe but loose in the grey pipe. Continuing with the repair all fittings were crimped. When the water was turned on the grey crimps all leaked. It appears the grey piping is a slight bit larger on the inside. Is the grey piping becoming obsolete? Are there fittings that will convert the grey to the white? Camping World and most places are only carrying the white pipe. Where is the best place to find the grey pipe? Help! Denney, (Lehigh Acres, FL)
Denney, indeed, the older, gray, polybutylene water tubing is no longer available. The white tubing is called cross-linked polyethylene (PEX) and has a different diameter than the older PB. Thankfully there are “transitional” fittings available that will successfully mate the two types of piping together. One company producing them is called Flair-It. They are available at many online retail outlets, as well as most RV accessory stores. 
