High Quality Content by WIKIPEDIA articles! Osmoregulation is the active regulation of the osmotic pressure of an organism`s fluids to maintain the homeostasis of the organism`s water content; that is it keeps the organism`s fluids from becoming too diluted or too concentrated. Osmotic pressure is a measure of the tendency of water to move into one solution from another by osmosis. The higher the osmotic pressure of a solution the more water wants to move into the solution. Pressure must be exerted on the hypertonic side of a selectively permeable membrane to prevent diffusion of water by osmosis from the side containing pure water.