Black deposits in low flow toilets

[Terry]

Closet tank to bowl bolts.
You can buy new brass bolts for that at any hardware store. It's a very generic part.
I see so many toilets from fifteen years ago that used steel bolts that will eventually rust out completley. It's a shame that for a matter of pennies, they push the homeowners into replacing parts that should have lasted decades.

 

[PlumbingGal]

I have the black streaks in only one of my four toilets. It happens to be the one used most often and is a cheaper American Standard Cadet. I was told the streaks occur because the insides where the water runs down through the holes when flushed are not glazed, which causes water and bacteria to build up. The other three pricier American Standard models don't have the streaks and I'm not sure if the inside chambers are glazed.

 

[Sponsor]

 

[Terry]

I have the black streaks in only one of my four toilets. It happens to be the one used most often and is a cheaper American Standard Cadet. I was told the streaks occur because the insides where the water runs down through the holes when flushed are not glazed, which causes water and bacteria to build up. The other three pricier American Standard models don't have the streaks and I'm not sure if the inside chambers are glazed.

It could also be rusting tank bolts, or black rubber washers for the tank bolts. I would lift the tank lid and take a look.

American Standard with rusting bolts.