I have a musky smell in my powder room. The toilet in this room is an American Standard one piece comfort height and sits on a marble floor. I have gone on line and read many reasons for smell and remedies. I tried using bleach tablets in tank (blue ones) and this did not work. This past weekend I removed all internal parts in the tank and scrubbed it clean with a scour pad and ammonia. The inside of the tank looked brand new. I then removed the toilet from the floor. There wasn't any signs of moisture under the toilet. The plywood that was visible around the marble was dry as a bone. I cleaned the flange and bottom of toilet until all was was removed. I installed a double thickness wax ring and replaced all the internal parts in the tank with new. I did not put a bleach tablet in the tank. I checked the room yesterday evening and the smell is back. I looked under the rim in the bowl and the outlet holes had very small stains (brownish) at several of them. Is there any way to brush out the inside of the rim? And or is there something I am missing? Do the design of thes American Standard toilets have a history of this problem.

Thanks

I don't think it's the toilet. Sewer gas smells like a cross between a fart and someone boiling cabbage. Does that room have a vent to the outside and is it used frequently? Does the door remain open when its not being used?

It is an interior room with fart fan. The door remains open and toilet and sink are used almost daily.

I'm guessing that's more of a re-circulation type fan rather than one that vents outside or do you know? Where I'm going with this is mold or some other crud that might be causing the odor. Some of those re-circulation type fans have filters in them that might be growing some nastiness.

Something I just thought of....is there a vanity and have you checked in it for any signs of a drain leak?

If there is an AAV under the vanity, it may have lost the seal. How is the vanity vented?