Water reabsorption in renal tubules varies at different levels. The maximum reabsorption is at:
PCT
Collecting duct
Descending Loop of Henle
Ascending limb of Henle
Sites of water reabsorption in the kidney: Proximal tubule (65% of the filtered water) Descending thin limb of Henle's loop (10%) Collecting-duct system (where the fractional reabsorption is the most variable) Ref: Eaton D.C., Pooler J.P. (2009). Chapter 6. Basic Renal Processes for Sodium, Chloride, and Water. In D.C. Eaton, J.P. Pooler (Eds), Vander's Renal Physiology, 7e.