I was eating in the kosher dining hall (because it often has better food than the goy hall) and, after I finished drinking from the water bottle I had brought with me, a Jew walked up to me and told me that I wasn't allowed to have my water bottle out in there and instead I had to drink water from their pitcher.
I tried to Google an explanation, but as far as I can tell, water is kosher. Is this some sort of Passover thing or have I been being anti-Semitic since I have been going there?