On average, it takes the human body approximately two to three hours to excrete a liter of water through the bladder. This is dependent on several factors, including the absorption of water, the components in the water, if dehydration is present, the time of day and the general health of the person.
Fluid is not absorbed as well by those who are experiencing continuous loss of fluid, as is the case with diarrhea or vomiting. Pure water passes through the body more quickly than water containing components, such as salts, that slow its excretion down. Dehydration causes the body to retain more water in order to compensate for water loss. When dehydration is present, urine production decreases until enough water is consumed to continue its output. Dehydration may occur when strenuous exercise has taken place, such as playing sports outdoors, or when not enough water has been consumed. The time of day affects urine production, which generally increases when the person wakes up, assuming he drinks an equal amount of fluids throughout the day. Healthy people excrete water more regularly than those with conditions that affect urine output, such as kidney or heart disease, in which water is retained in tissues versus being excreted.