I drink from my metal tank and suffer no ill consequences. If on a short weekend trip, I'll fill from my own well or, if I time it right, from a local spring. The water may stay in the system for a season with no observable change in quality.
I sanitize the whole system once a year. With my pressurized system, it is very easy to do. I know some folks don't sanitize the system but every new water softener I've installed recommends it, whether on city water or not. If you've ever done some copper plumbing there wouldn't even be a question about sanitizing/flushing the system. No one, AFAIK, likes debris and flux in their water.
Before anyone corrects me on material in an RV system, I know most RV's do not have copper pipe. The BIL of the guy that makes the copper pipe makes your PEX. If he has a salmonella infection, he blames it on his renter, the guy that makes tanks and has a part time job at the poultry slaughter house.