If the water is expired, of course it is not suitable for drink. So you should try consume it all before its expiry.
I'm curious why you haven't yet plugged in the water dispenser for usage so far. I got 1 water dispenser for mixing milk powder for my babies and hot beverages for the family, and they all happy with using it, due to convenience of having chilled and hot water, even not to mention that I got an very attractive discount from the Salesman when I called by an expo.