I have some vague, probably erroneous memory of seeing some hot water fixture that said it wasn't meant for potable water, which made me believe that residential hot water in the USA may have different standards than cold. It might've been something related to the hot water heater. I know things like garden hoses and spigots do NOT meet the same standards for potable water and often have labels that make it clear.
Anyway, does hot water plumbing meet the same standards as cold water?
There may be other reasons why you don't want to drink hot water (eg, it might leach more easily), but I'm just curious about the standard practices in the USA.