Scale your water to your body weight — roughly 35-45 mL per kg a day (e.g. 40kg → 1.5L, 100kg → 4.5L) — and bump it up further on heavier training days.

noli's read

The chart's numbers (roughly 35-45 mL per kg, e.g. 100kg → 4.5L) land close to an estimate commonly used in clinical nutrition for adults' baseline fluid needs (often cited around 30-35 mL/kg in hospital and geriatric protocols), so the ballpark isn't invented. That said, population guidelines (Institute of Medicine, echoed by Mayo Clinic) don't scale linearly with body weight: they set an average range of about 2.7L/day for women and 3.7L/day for men, all beverages plus roughly 20% from food included — a figure that shifts mainly with activity, climate, and diet, not weight alone. Presenting a fixed chart as THE universal answer oversimplifies a physiology that actually self-adjusts day to day through thirst. The 'more training = more water' add-on is well-grounded and consistent with the exercise-hydration literature. Verdict: mixed — the ballpark is defensible and more rigorous than '8 glasses' or 'a gallon,' but it's presented with a precision the science doesn't actually validate.

the sources

1. 1Valtin H 2002