Final answer:
The kidneys have the primary control over the body's water levels, regulating hydration by adjusting urine concentration and hence water balance. ADH aids the kidneys in water reabsorption, crucial for hydration. Hydration is balanced by controlling intake versus output through various body functions.
Step-by-step explanation:
To maximize hydration, control of the body's water concentration is key. The organ with primary control over the amount of water in the body is the kidneys. The kidneys regulate water balance by adjusting the concentration of urine; in response to the body's hydration levels, they can conserve water if the body is dehydrated or expel excess water when needed. Hormones such as the antidiuretic hormone (ADH) play a vital role by increasing water reabsorption by the kidneys, facilitating the retention of water and aiding in hydration.
Mechanisms like the sensation of thirst also contribute to encouraging water intake, which is balanced by the water the body loses through urination, defecation, sweating, and respiration. Maintaining this balance is critical for homeostasis, which includes not only managing fluid levels, but also maintaining consistent blood plasma osmolality, temperature, pH, and solute concentration.