Whether you stand or sit while drinking water, it gets absorbed in the body rapidly.
Dr Phillips explains: Let me tell you what happens to water when it is consumed orally – whether you stand, sit or close or open your eyes while drinking it.
Water has basically 100% oral bioavailability, and is absorbed rapidly through the gut wall, mainly in the small intestine. Absorption is near-complete, rapid, and mainly occurs in the early part of small bowel.
Absorbed water is then distributed proportionally in the body fluid compartments:
66% into the intracellular fluid
25.5% into the interstitial fluid
8.5% into the circulating blood volume
Elimination is through kidneys, where the filtered fraction is reabsorbed by a highly regulated mechanism.