black specks in commode after flush

[bonjour609]

Our commode has had for a long time now black flecks appear in it. It appears that they come in with the clean water when flushed. I brush and scrub and get them all cleaned out. Then, not two days later enough of the black specks are in there again that I have to do it all again. We replaced a commode last year which started not working. The plumber said it might have been all the black stuff that had caused a problem, but he had no idea what caused them. We even called the water company who did a check on the drinking water, but they found no problems. There are no black specks in any of the sinks or tubs, just in the commodes. They are in each of the three commodes though. The house is about 20 years old and this has been going on for around a year that we've noticed, but it's getting worse all the time. These specks are very annoying and somehow end up also on the wall when trying to clean them out of commodes, there are so many of them.
Does anyone know why this problem or how to fix? I wish it would be simply replacing a filter but there are no filters in commodes.

[Pulpo]

Is there an old style float or flapper that's pealing in the tank? Also, look at the sides of the tank. I bet they are black as well.

[Milemaker13]

We get the same thing at our house. We use a bleach tab in the tank and it gets rid of the black spots. We think they are some kind of water mold... definatly growing on the bowl, not simply deposited there. We just bought this old house and have since replaced all of the old pipes with new copper, but there is still a bit of old lead pipe going to the toilet. Maybe it has to do with the old pipes and old toilet.

Talk a much closer look next time... Does it look more like rings of mold or just flecks of black stuff? Drop in a bleach tab and then scrub... I'm betting you will be spot free for about 3 months!