allendon!
Can you post a picture? Is it an older leaf? Or a newer younger one? If an older one, that would/could be quite normal.
Unless you live in an area that has really dreadful water, I would think tap is fine. I often water with tap water, but I do let it sit for at least 24 hours for chlorides, fluorides, and such to dissipate, and allows it to come to room temperature.
