In renal physiology, reabsorption or tubular reabsorption is the process by which the nephron removes water and solutes from the tubular fluid (pre-urine) and returns them to the circulating blood. ... The kidneys sense low blood pressure. Release renin into the blood. Renin causes production of angiotensin I.

Why is water reabsorbed by the body?

Having filtered out small essential molecules from the blood - the kidneys must reabsorb the molecules which are needed, while allowing those molecules which are not needed to pass out in the urine. Therefore, the kidneys selectively reabsorb only those molecules which the body needs back in the bloodstream.

What would happen if there is no water reabsorption in kidney?

If there will be no tubular reabsorption in nephrons the useful things would get off from the body with urine (urea and water formed urine). Selective reabsorption allows useful materials to get into capillaries again and the body will use them for further processes.