Clean the water heater or sanitize the fresh water tank first?

do the hot water tank first, the flush it out good, then do the bleach.  I am not a fan of bleach anymore but lots of people use it so do it last after everything is clean, then flush the heck out of it after to get rid of the "bleach"   most rv drain lines are 1/2" pex, but there could always be an exception.