The importance of diet water on skin’s physiology has been explored as a marketing argument specially for cosmetic and nutritional claims, while many studies have shown that the amount of water present in food and produced by metabolic pathways, is not sufficient to meet regular daily needs . The normal water intake is determined by a complex set of highly sensitive neurophysiological mechanisms ruling osmolarity and water balance. It varies between individuals but, unlike other fundamental nutrients, daily water requirements are not clearly identified. And the relative impact of this nutrient over normal in vivo human skin is far from being established. So, the present project intends to respond to these specific questions. Twelve healthy volunteers, female, participated in the study (mean age 23.2±1.85), after informed written consent. All procedures respected Helsinky principles and respective amendments. In order to assess the total amount of water consumed, daily, volunteers were asked about their regular dietary habits. Based on a survey of food frequency previously validated, it was possible to identify 2 groups of patients regarding their water consumption through regular diet (a) those consuming less than 500ml of water/day (b) those consuming more than 500ml of water/day. A stress test was designed involving the additional daily consumption of 2liters of water, during 4 weeks. This amount corresponds to the referenced water consumption recommended by the Dietary Guidelines for Americans 2010 Report, and to the European Food Safety Authority (EFSA). Representative variables were transepidermal water loss (TEWL, measured by Tewameter TM300, CK electronics), epidermal hydration (measured by MMSC, Delphin UK) and skin’s biomechanics (Cutometer CM575, CK electronics). Measurements took place at T0 (inclusion) T2 (2 weeks after beginning the test) and T4 (by the end of the test, 4 weeks after beginning) and involved several anatomical regions (face, ventral forearm, breast, abdomen and, external leg) . Statistical analyses were performed using SPSS 17 and a 95% level of confidence adopted. Data seems to suggest that variation of the dietary water intake may alter normal skin physiology in all anatomical sites. Significant changes on epidermal hydration are already detected at T2 and biomechanical descriptors seem to improve at T4. No significant changes were detected regarding the barrier function. The proposed methodology may be optimized to further explore the importance of water in our regular diet and normal physiology