Water Intake Calculator Articles

Why "Drink to Thirst" Fails at Altitude — and the Specific Contexts Where You Need More Water Than General Guidance Suggests

Altitude dehydration is real because respiratory rate increases and inspired air is drier — but thirst doesn't compensate fully, making trekkers a specific population where "drink to thirst" systematically underestimates needs. Here's the quantified altitude respiratory water loss (up to 1,200 mL/day at high altitude), the fever rule of thumb (each 1°C above normal adds ~20-25% water loss), why coffee's diuretic effect is smaller than its fluid content, and the specific kidney stone prevention fluid target (2.5 litres urine output daily).

Jun 30, 2026

Why You Don't Have to Drink 8 Glasses of Water a Day — and When You Actually Do Need to Drink More

The "8 glasses a day" rule omitted the very next sentence from its source: "most of this quantity is contained in prepared foods." Roughly 20-35% of daily fluid comes from food, making the actual drinking target lower. Here's why thirst is a more reliable hydration mechanism than most people think (in healthy adults in normal conditions), the specific situations where following thirst isn't enough, and why urine color is a better real-time hydration indicator than tracking millilitres.

Jun 23, 2026

Hyponatraemia and Endurance Sports: When Plain Water Isn't Enough — And Drinking Too Much Becomes the Risk

"Drink more water" advice has a limit — exercise-associated hyponatraemia, caused by drinking more fluid than you lose during prolonged exercise, has caused documented fatalities in endurance events. Here's why thirst-based drinking is now generally preferred over fixed schedules, who's at higher risk, and what role sodium intake actually plays.

Jun 16, 2026

Hydration and Electrolytes: When Plain Water Isn't Enough During Exercise

Multiple Ironman athletes were hospitalised from drinking too much plain water — exercise-associated hyponatraemia. Here's how electrolytes regulate fluid balance, when plain water is insufficient during prolonged exercise, sodium replacement guidelines, and the "drink to thirst" vs. scheduled drinking debate.

Jun 10, 2026

How Much Water Do You Actually Need? The 8-Glasses Rule Examined

The 8-glasses-a-day rule has almost no scientific basis. Here's how the body actually regulates hydration, what genuinely affects your water needs, how to use urine colour as a real-time indicator, and when the rule breaks down.

Jun 8, 2026

Water Intake Calculator — Find Your Personalised Daily Hydration Target

Learn how daily water intake needs are calculated, why the 8-glasses rule falls short, how climate and activity affect hydration, and how to use a free water intake calculator for a personalised target.

Jun 6, 2026