Glomerular filtration rates:

The amount of filtrate formed by kidney per minute is called GFR. It is about 125 ml per minute, i.e. 125 x 60 x 24 = 180 liters per day.

Excess of water:  More filtration due to high blood pressure but less re-absorption because ADH is not released.

Low water level: When water level of plasma falls, then blood pressure decreases so less filtration of blood and more re-absorption because ADH releases.

By all these, water level of blood maintains and water of body is fully conserved.