As of 2015, only one study has examined the exact benefits of long-term water intake on the appearance of the complexion; published in 2007 in the International Journal of Cosmetic Science, the study found that drinking 9.5 cups of water per day for four weeks altered the skin's density and thickness. Researchers consider the results contradictory because those who drank mineral water showed improved complexions, while those who drank tap water had little benefit.
Regardless of the contradictory results of the 2007 study, nutritionists and doctors still suggest drinking adequate water to keep the body hydrated. The definition of proper hydration is consuming enough water to replenish moisture and electrolytes lost during the day. Keeping the body properly hydrated helps the skin appear less dry and wrinkled.
The best method for improving the complexion involves combining water consumption with exercise and moisturizer. Exercise improves the flow of blood to the skin, and the water flushes toxins out of the body, resulting in a clearer complexion. To maintain moisture in the skin, dermatologists recommend applying moisturizer.
One test of adequate hydration involves pinching the skin on the back of the hand. If the skin quickly bounces back, the body is properly hydrated.