That I can answer. He tried the same batch of dough prepared two ways, one boiled in Chicago water and one boiled in NYC water, but otherwise prepared identically. He preferred the taste of the bagels boiled in NYC water (and could tell the difference, he says). It was a disciplined taste test, as he told it to me.
I'd like to see the test repeated with doughs made identically, one with chicago water and one with ny water, then boil each in chicago water, then boil each in ny water.
And I'd like to see a variety of tasters as well. Maybe my taste buds are dead, but I really don't think I can pick up on some of the subtle differences others can. Though if the bacterial contaminants in water play a bigger factor than I think they do, maybe it does make a marked difference...
Taft