Overview

• Large-scale research found that individual water needs vary and most people require about 1.5 to 1.8 liters daily rather than a flat two-liter prescription.
• The Deutsche Gesellschaft für Ernährung recommends around 1.5 liters per day while the Akademie für Sport und Gesundheit suggests 30–40 milliliters per kilogram of body weight (approximately 2–3 liters).
• Cardiologists from the Bundesverband Niedergelassener Kardiologen caution that fluid overload in heart-failure patients can lead to complications and advise limiting intake to roughly 1.5 liters.
• Hydration experts now emphasize consuming lukewarm, low-sugar electrolyte beverages to maintain mineral balance and improve fluid absorption.
• YouTuber Lisa Sophie Laurent’s week-long experiment of three liters a day yielded improved skin moisture and concentration but underscored practical challenges such as frequent bathroom breaks.