The proximal convoluted tubule (PCT) reabsorbs approximately 65-70% of filtered water along with essential solutes like sodium and glucose. This segment is highly permeable to water due to abundant aquaporin-1 channels, enabling efficient water reabsorption following solute transport. The osmotic gradient created by active solute reabsorption drives passive water movement, making the PCT the primary site for water recovery to maintain fluid balance. This function is critical clinically, as disruptions here can lead to significant volume depletion and electrolyte imbalances.

Reference: Guyton and Hall, Textbook of Medical Physiology, 14th Edition.