Yes, drinks are allowed in the library. However, they should not be used to attract bugs or flies.
Actions that you should avoid when having a drink around books:
-Drinking and discarding the contents of a can down an open book (especially acidic sodas).
-Drinking and spilling juices over books.
-Carrying your cup of coffee or hot drink while reading or studying for too long without putting it on something like a coaster under your saucer so that it doesn't leave ring marks on the desk/table top surface.
Rules for handling drinks at the Library: If you need to carry cups from your car to inside, bring soup cups from home if possible.