via reddit.com
Got a little nervous after reading this because I currently live in NYC, did some fact-finding, and it turns out that since most of the various water creatures are microscopic, the water is probably kinda all right (it’s still highly preferable to filter it first)
since you can sometimes see them (and as such they’re not microscopic) it is highly preferable to filter first
As with literally everything else, there is considerable debate as to whether or not filtering the water is required. (Source: I’m an Orthodox Jewish New Yorker, and my rabbi does not consider the filter necessary, or even strongly recommended.)
If you are in New York and concerned about the issue, your best bet is to consult your own rabbi.