Recently moved into a rental, after moving in found mold on some wood in basement. Near this mold source there are also pipes covered in a substance that looks like soot, black and powdery. Landlord says they are steel pipes and this is what they look like when they corrode but I have my doubts that this is correct. And even if it is, what does this mean for the internal state of the pipes? The water that comes from the tap is also a bit brown when seen in large quantities such as filled bathtub. Not sure of these are the water pipes that are covered but I think they might be. Landlord has been reluctant to do a darn thing about the mold also. He sprayed it with sporicide but never cleaned it up and is getting agitated that I keep asking for it to be dealt with.

Not all mold is harmful. Penicillin is a Mold derivative. Mold needs a food source, wood or paper for example, not steel or iron. More than likely this is just oxidation. As far as brown water, this is iron oxide, rust. Common if on a well. Harmful to drink, no. Most people take a Vitamin and that has Iron in it, usually as a sulfate. Our mountain house is on a well and I have to change the house filter or is slowly becomes brown, most noticeable in the tub.