I was intrigued by the article that BossCamper wrote, very interesting study without much of the info on the controls. I will take it with a grain of salt.
In a physics class some time ago, the instructor was explaining the Browning Theory of Molecular Motion, for those who have not heard or read about it, simply stated, "All molecules are constantly in motion". An example he gave supports many of the posts made here. He stated that if you put one molecule of gold on the end of a lead ingot, eventually, it will make its way to the other end of the ingot.
Leaching is the theory in action. So what can you take away from all this rhetoric, sometime in the future, you will ingest every different molecule in the hose or pipe your drinking water comes from. It is not going to be constant in value and in most cases, there are quite a few variables that can effect the rate of motion and leaching as well as the fact that some molecules do not attach well to a molecule of H2O.
Another interesting thing to ponder, how many people have sprinkler systems for their lawns, landscaping and GARDENS? How many are using PVC pipe? Can the chemicals from the PVC pipe leach into the water and feed a garden thereby allowing the food stuffs in a garden to absorb and pass on hazardous chemicals.
Kind of pie in the sky isn't it?
I use the white hoses for filling my tank, I flush the noses before filling, and I try to keep them cool(impossible in an RV) and out of direct sunlight and drained as well as I can. I seldom have my water hose hooked up as we are more travel oriented than destination oriented and hook up, un-hook are just extra steps for an overnight. My wife wants her favorite bottled water so we seldom drink water from the tank, but we brush our teeth and rinse with it and I make my coffee from it every morning.
Just my never to be humble way of saying use common sense and do everything in moderation.