Any Home Brew, or Catering supply shop will have this pipe, but the standard Cold Water pipes that every new caravan is fitted with are quite adequate, and certainly of a good standard.
If you're worried about it, why not simply change the pipe, which you can get easily and cheaply from any caravan shop.
We always flush out our whole water system during the spring using beer pipe line cleaner, which sterilises and cleans the pipes very well. After every three years, we replace the pipes as a matter of course, just for safety.