If I were to ask the waitstaff at a restaurant for another "glass of water", I would expect them to either refill my glass or bring a new glass, whichever is convenient for them. Likewise if I point to the glass (or it's the only one on the table and it's visibly empty) and ask for another "glass". If, however, I ask for another "water glass", I would very specifically expect that the vessel itself be replaced.