Final answer:
On average, water loss in adults is greatest from urination, followed by perspiration, insensible water loss from skin and lungs, and finally feces production, which contributes the least to water loss unless diarrhea is present.
Step-by-step explanation:
The average adult loses water daily in the following order from the most to the least: urination, perspiration, insensible water loss from skin and lungs, and feces production. Typically, an adult produces about 1.5 liters of urine per day. Perspiration can vary, but on average, an adult may lose roughly 2 to 3 liters of water per day overall, including water lost through sweating. Insensible water loss, which is water loss through the skin and air expelled from the lungs while not perceiving it as sweat, also contributes significantly. Feces generally cause the least amount of water loss unless there is an illness such as diarrhea.
Additional factors include environmental conditions and health status, which can increase water loss through sweating, vomiting, diarrhea, or when suffering from kidney disease or fever. For instance, water loss is more significant in cases of diarrhea and vomiting, and can be severe enough to cause dehydration, particularly in young children or infants.