Roofing/oily residue runoff from asphalt shingles
We just had a new three tab asphalt shingle roof installed, after a severe hail storm in south texas. About a month after the roof installation, we had a very light rain shower and I noticed a puddle on the driveway that had a rusty brown oily residue film on top. After the water evaporated, it left a brown stain on my driveway. Two weeks later we had a big thunderstorm. I collected the rain coming down off the roof in a clean bucket and transferred it to a clear plastic bottle. The water was the color of dark brown tea. Is it normal for a brand new roof to have this type of runoff? Could it be defective shingles? Who would be able to insure quality shingle material was used on my roof?
Based on your description, the brown water is runoff from rusted flashing. Very likely your chimney flashing.
When it rains, the water that touches your chimney flashing beccomes stained with the rust and that's why it turns brown.
This tells me the roofers did not replace your chimney flashing, It could also be rusted drip edge or step flashing but more likely the chimney flashing.