By Mano 
For most healthy Australian adults, a practical daily guide is about 2.6 litres of fluids for men and 2.1 litres for women. That equals roughly 10 and 8 Australian cups respectively, using a 250 mL cup. Your actual requirement can be higher or lower depending on exercise, weather, pregnancy, health and what you eat.
There is one important detail behind those numbers: they refer to fluids, not necessarily litres of plain water.
Australian Nutrient Reference Values separate fluid intake from total water intake.
For adult men, the Adequate Intake is approximately:
- 2.6 L from fluids
- 3.4 L total water from food and fluids
For adult women, it is approximately:
- 2.1 L from fluids
- 2.8 L total water from food and fluids
The Australian data behind these recommendations estimate that roughly one-quarter of adults’ water intake comes from food.
So if you are drinking water, tea, coffee or milk and eating foods that contain plenty of water, you do not need to add another several litres of plain water on top simply to reach the “total water” figure.
A fixed number is useful as a starting point, but your needs change.
You are likely to need more fluid when you are physically active, sweating heavily or spending time in hot or humid weather. Illnesses involving fever, vomiting or diarrhoea can also increase fluid losses.
Food matters too. Fruit, vegetables, soups and many other foods supply water, while drinks including milk, tea and coffee also contribute to fluid intake. Water remains the simplest everyday choice because it hydrates without added sugar or alcohol.
Australian guidance does not provide one universal “millilitres per kilogram” formula that accurately determines everybody’s requirement. Treat online water calculators as estimates rather than precise prescriptions.
You usually do not need to spend the day measuring every millilitre.
Look at how your body is responding.
Pale yellow or straw-coloured urine generally suggests you are well hydrated. Darker yellow urine can be a sign that you need more fluid, particularly when combined with thirst, a dry mouth, tiredness, headache or light-headedness.
Urine colour is not perfect. Vitamins, medicines and some foods can change it, so an unusual colour does not automatically mean dehydration.
During exercise or very hot days, drink regularly rather than relying solely on becoming strongly thirsty first.
Not everyone.
“Eight glasses a day” is memorable, but there is no universal eight-glass requirement.
Interestingly, Australia’s general guidance for adult women is close to eight 250 mL cups of fluid, while adult men are closer to 10 cups. But those cups can include fluids other than plain water. Individual requirements also change with climate, activity and health.
So the useful question is not “Did I force down eight glasses?” It is whether your overall fluid intake is keeping you adequately hydrated.
Fluid requirements rise during these stages.
For adults aged 19–50, Australia’s Nutrient Reference Values give approximately 2.3 L of fluids per day during pregnancy and 2.6 L during breastfeeding, with additional water also coming from food.
These are population-level guides rather than personal medical instructions.
Drinking far beyond what your body needs does not make you “extra hydrated.”
Excessive water consumption can, in rare cases, dilute the sodium in your blood and cause hyponatremia. This is particularly relevant when very large amounts are consumed around prolonged intense exercise.
People with chronic kidney disease, heart failure or liver disease may also need specific limits or targets because their bodies may handle excess fluid differently. Follow your clinician’s advice rather than a generic online target.
For an otherwise healthy adult in Australia, begin with the general fluid guide:
Men: about 2.6 L or 10 cups per day
Women: about 2.1 L or 8 cups per day
Then adjust naturally for heat, exercise, illness, pregnancy or breastfeeding and pay attention to thirst and urine colour.
The target is good hydration—not reaching an arbitrary number at any cost.
For more practical health information, browse our Health articles.
This information is general and is not a substitute for individual medical advice.