Accurately calculate how much water you need each day
Drink 1-2 glasses of water right after waking. Drink water 30 minutes before meals to aid digestion. Hydrate well before and after exercise. A pale yellow urine color indicates good hydration. Caffeinated drinks have a diuretic effect, so do not count them as water intake. In hot weather or during exercise, drink 20-50% more than usual. Sipping small amounts frequently throughout the day is more effective for absorption than drinking a lot at once.
Baseline intake is 30-35ml per kg of body weight; this calculator uses 33ml/kg as the baseline. It then multiplies by gender (female ×0.95), activity level (sedentary ×1.0 to very active ×1.7) and climate (cold ×0.9 to hot ×1.3) to produce a personalized amount. The recommended range runs from 25ml/kg (minimum) to 40ml/kg (maximum). For example, a 70kg person at moderate activity and a normal climate is advised about 2.4-3.0L.
Water is involved in nearly every body function — temperature regulation, nutrient transport, waste removal, joint lubrication and digestion. About 60% of the body is water, and a deficit of just 2% can cause reduced concentration, fatigue and headaches. Proper hydration supports kidney health, prevents constipation and helps skin health. However, with kidney disease or heart failure you may need to limit fluids, so consult a doctor.