Recommendations for carpet tile installation
You can make the floor water resistant by varnishing it. Two or three coats should protect it from most damage, especially if you lift the affected tiles straight away. Most damage is done by the prolonged contact of the water with the floor. Are you expecting a lot of spillage?

This does mean that you might want to consider not sticking the tiles down or only using a very light adhesive. If the tiles are well fitted and cover all of the floor area there shouldn't be any lateral movement in the tiles themselves.