Nephrologist challenges daily water intake myths

Spanish nephrologist Borja Quiroga suggests that the common recommendation to drink 1.5 to 2 liters of water daily lacks a clear scientific origin and may not apply to everyone. Individual fluid needs vary based on lifestyle, physical activity, ambient temperature, and overall health.

For healthy, sedentary adults not exposed to high temperatures, a baseline estimate is approximately 1.2 to 1.3 liters per day. This figure accounts for roughly 0.5 liters required by the kidneys to eliminate toxins and 700 to 800 milliliters lost through skin, respiration, and insensible perspiration. Additionally, the body receives hydration from food sources such as fruits, vegetables, soups, and yogurt.

Quiroga warns that excessive water consumption is not always beneficial. While insufficient intake can lead to dehydration, overconsumption can cause hyponatremia—a dangerous drop in blood sodium levels that may result in nausea, headaches, or cramps. He notes that lighter-colored urine does not necessarily indicate improved kidney function, as the kidneys naturally adjust urine concentration to meet bodily needs.