I believe you are asking the concept in which water tends to move in a cell, which is called <u>osmosis</u>.
Cells have semipermeable membranes, which means that not all substances are able to enter or leave the cell.
<u>Osmosis</u> permits <u>the movement of a solvent across this semipermeable membrane</u> (see image below). During this process, water moves from an area of high concentration to an area of lower concentration of water.