Hmmm.... not sure on that one. I live in an apartment building, and who knows what's going on in the bowels of it. But so far I've only seen hot water tanks in the basement.
I do know that the water in Chicago is not exactly "perfect."

I get a lot of pink rust stains in my dish drainer, for example. I want to treat the orchids well, but I can't exactly imagine myself carrying gallons of water up all the steps from the grocery store for them when I don't do it for myself. (I'm evil.)
So if water is the problem, how to handle? I have LOTS of other plants that drink the same water, and they are doing just fine.

My main worry is that this is some type of a virus that's going to wipe out my orchids. But I do love to go over the deep edge with worry a lot

, so the thought that this could just be water is making me feel a lot better.
If it is just water, would I just cut off the leaves?