I bought this house three years ago with a well with moderate hardness and iron. Electric HWH is who knows how old. (Mor-Flo Ind. S/N 704946, I thought someone said the serial number tells the mfg. date?) At the time the water softener was barely removing hardness and probably no iron. Put in a new softener last summer and water is noticeably better and tests good. Around the same time we put in new white Glenwall toilets, white cast iron tub, and white porcelain pedestal sink. The tub and sink, along with the dishwasher have iron staining after a while of use, several weeks. The toilets and clothes washer do not have the iron stains.
To me, the obvious difference is the fixtures using hot water have the stains and those using only cold water do not. Could there be a build up of iron in the HWH from years of use, or possibly internal rusting of the HWH tank causing the fixture staining with the hot water? I'm willing to just replace the heater and give it a try, it looks old as heck anyways. Does my theory sound plausible?