The cell membrane is made up of a "lipid bilayer" This means that there is are two lipid molecules, each of which has a hydrophilic(water loving) head and hydrophobic(water hating) tail. In the membrane there are 2 molecules facing away from each other such that the head of the lipid faces out and the tail is on the inside. Therefore, with the hydrophobic tail on the inside or center of the membrane it would repel water.
