How Much Water Should You Drink a Day?

There is no single perfect amount

Daily fluid needs vary between people. Body size, activity, weather, pregnancy, breastfeeding, diet and health can all change how much fluid someone needs.

That is why a fixed rule such as “everyone must drink eight glasses” is too simplistic.

Want to try the idea yourself? Use the Water Intake Calculator.

Water vs total fluids

Hydration does not come only from plain water. Other drinks and water contained in food also contribute to total fluid intake.

Plain water is a simple choice because it hydrates without adding sugar or calories, but the overall picture is broader than counting glasses of water alone.

Exercise and hot weather

Sweating increases fluid loss, so exercise and hot conditions can raise hydration needs. Longer or more intense activity can also involve electrolyte losses.

The amount needed depends on how much you sweat and the conditions, so one fixed exercise adjustment will not suit everyone.

Can you drink too much water?

Yes. Drinking excessive amounts very quickly can be dangerous because it can dilute sodium levels in the blood. More water is not automatically healthier.

People with certain kidney, heart or other medical conditions may also receive specific fluid advice from a clinician.

Use an estimate sensibly

The Water Intake Calculator can give a practical starting estimate based on the information it asks for. Treat it as a guide rather than an exact prescription.

Thirst and urine colour can sometimes provide useful everyday clues, but seek medical advice if you have concerns about dehydration, excessive thirst or fluid balance.