water takes up more volume than ice. Fill a glass with lots of water, put ice in it and wait for the ice to melt, it will over spill the edge of the glass (Wrong).
Ice is expanded water (so to speak), it displaces exactly the same amount of water after it melts in the glass.
Now if you overfill the glass with crushed ice and then fill it with water to the brim you may see spillage upon melting.