A practical general approach for many adults is starting with one bottle per day (about 200–250 ml), and adjusting to one to two bottles based on needs and tolerance. The key variable is sodium: some mineral waters are high in sodium, and multiple bottles can meaningfully increase total daily sodium intake. After heavy sweating, adding a bottle—preferably a low-to-moderate sodium option—can make sense. If you have hypertension, kidney disease, or fluid retention, intake should be more limited and label-driven.