Final answer:
Hormones and the kidneys primarily control water balance in the body.
Step-by-step explanation:
The two primary factors that control water balance in the body are hormones and the kidneys. Hormones such as ADH (antidiuretic hormone), vasopressin, oxytocin, and aldosterone play a crucial role in regulating water reabsorption and excretion in the kidneys. The kidneys, on the other hand, control the concentration of urine to reflect the body's water needs, conserving water when dehydrated or eliminating excess water when necessary.