Some states may have their own requirements, wouldn't know, haven't worked in every state.
I've worked in health care maintenance, as a care provider, and as an administrator. I retired the last time 5 years ago, so I may be dated.
On the national level the two main ways to get a hospital accredited to provide care are JCAHO and HFAP (now there are other options). For water, both referenced back to EPA and Public Health guidelines, but it was on the hospital to provide evidence of testing with results within compliance standards.
End of trivia ...
Flush your water heaters at least once a year in any manner that makes you happy.