Hydration: How much fluid/water should you drink in a day?

We always get told that we need to drink more water, but how much should we really be having each day? Depending on who you talk to, you will probably get a different answer. It may even differ as widely as 2-4L per day.

Water accounts for 50-80% of body weight depending on lean body mass. It is an essential nutrient required for digestion, absorption, elimination of waste products as well as regulating body temperature.

Since everybody is different, there is no single level of water intake that would ensure adequate hydration and optimal health. When talking about hydration, we estimate total fluid intake and not just water alone.

To calculate fluid, aim for 35-45ml/kg/weight. For example, a person who weighs 60kg would need between 2.1-2.7L fluid per day. This fluid is not just water – any milk, coffee, tea, flavoured drinks, etc, all fall under this category.

Water will always be a better source of hydration as it contains no calories. Generally, if we aim for half of our total fluid intake per day to come from water the rest of our fluids can be made up with other drinks (of course, limiting sugar sweetened beverages where possible).

Use your judgement on how much water/hydration you may need depending on level of activity/sweat loss and weather conditions in order to prevent dehydration.


Australian Government: National Health Medical Research Council. 2014. Nutrient Reference Values for Australia and New Zealand: Water <https://www.nrv.gov.au/nutrients/water>