You could have black mold in the water supply from the pipes or tank.
Black mold in the toilet.
There could be cracks in the ceramic of your toilet.
These cracks give black mold a place to stick grow and flourish.
But if your toilet has good ventilation or fans that can make the air flow smoothly the chance of mold is pretty much low.
First flush the toilet and pour a cup of bleach into the bowl when the water begins to return.
If you see black mold growth in your toilet you ll need to take steps to remove the mold and prevent it from returning.
Black molds thrive in areas that have a higher exposure to sugar.
In other words it is a good source of energy for the fungus residing inside the toilet bowl.
The main black mold in toilet causes is the ventilation.
Basically mold in the toilet bowl gets more energy when there is high glucose content in the urine and this is majorly in the case of diabetic individuals.
You may end up scrubbing the black stuff off the toilet only to find that it has returned two to three days later.
The black discoloration that forms often indicates a problem with the water such as mold spores bacteria or minerals.
A toilet tank can provide the moisture mold needs to grow.
Next using a scrubber begin to scrub around the toilet bowl and edges of the seat.
The water in your toilet tank should be clear and free of debris or contaminants.
Rust on the pipes can also cause condensation which leads to black mold.
Black mold can create health problems for those living in the house especially if they have immune system or respiratory problems.
The best method for removing black mold from the bowl is using bleach removers.