You can get all kinds of drinks in the canteen for a very cheap price. There is of course the Grolsch Pils draft beer, but there are also 3 other special draft beers, and ~10 special beers from a bottle. Additionally you can also get about any softdrink you can think of.
Please note that you are not allowed to take your own alcoholic beverages into the sportscentre! Your drinks will be confiscated when found. You are also not allowed to take any glass outside the canteen. If you want to take your drink to the stands in one of the halls, you need to take it in a plastic cup!