Okay, so I just double-checked, and the cold, untreated well water at the outdoor tap does seems to have less smell than the cold kitchen tap water. Since both source flow through the pressure tank, could this point to the softener as a possible contributor? Not sure whether the pump guy disiCnfected the softener; I think he put the system in "bypass" before he ran the chlorine to the pumps . . . .
Anyone know how to disinfect a 14-year old Mark 89 Culligan (.7 ft3 resin)?