Question 1

How much water should I drink per day?

Accepted Answer

A common baseline is 30-35 ml of water per kilogram of body weight (about 0.5 oz per pound). For a 70 kg (154 lb) adult that is roughly 2.1-2.5 liters (71-85 oz) per day. Add 350-700 ml (12-24 oz) for every 30 minutes of intense exercise, and more in hot or dry climates.

Question 2

Does the 8x8 rule work?

Accepted Answer

The 8x8 rule (eight 8-oz glasses per day = 1.9 L) is an easy-to-remember rule of thumb that works for many sedentary adults. But individual needs vary with body size, activity, climate and health. This calculator gives a personalized estimate instead of a one-size-fits-all number.

Question 3

How does exercise affect water needs?

Accepted Answer

Intense exercise causes significant water and electrolyte loss through sweat. The American Council on Exercise recommends adding 12-16 oz (350-475 ml) of water for every 30 minutes of vigorous activity, on top of your baseline intake.

Question 4

Do I need more water during pregnancy or while breastfeeding?

Accepted Answer

Yes. Pregnancy increases total body water by about 1.4-1.8 L, and lactation requires roughly 700 ml/day of additional fluid to support milk production. We add 300 ml for pregnancy and 700 ml for breastfeeding on top of the baseline.